U.S. patent application number 10/958203 was filed with the patent office on 2005-07-07 for methods and apparatus for orthopedic implant preparation systems.
This patent application is currently assigned to Hudson Surgical, Inc.. Invention is credited to Goldstein, David B., Haines, Timothy G..
Application Number | 20050149038 10/958203 |
Document ID | / |
Family ID | 27569501 |
Filed Date | 2005-07-07 |
United States Patent
Application |
20050149038 |
Kind Code |
A1 |
Haines, Timothy G. ; et
al. |
July 7, 2005 |
Methods and apparatus for orthopedic implant preparation
systems
Abstract
Methods and apparatus for systems for preparing musculoskeletal
structures to receive an orthopedic implant.
Inventors: |
Haines, Timothy G.;
(Columbia City, IN) ; Goldstein, David B.; (Cream
Ridge, NJ) |
Correspondence
Address: |
Brad Pedersen
Patterson, Thuente, Skaar & Christensen, P.A.
4800 IDS Center
80 South 8th Street
Minneapolis
MN
55402-2100
US
|
Assignee: |
Hudson Surgical, Inc.
|
Family ID: |
27569501 |
Appl. No.: |
10/958203 |
Filed: |
October 4, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10958203 |
Oct 4, 2004 |
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09799325 |
Mar 5, 2001 |
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6695848 |
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09799325 |
Mar 5, 2001 |
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09261528 |
Mar 3, 1999 |
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6197064 |
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09261528 |
Mar 3, 1999 |
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08892286 |
Jul 14, 1997 |
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5879354 |
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08892286 |
Jul 14, 1997 |
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08649465 |
May 17, 1996 |
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5755803 |
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08649465 |
May 17, 1996 |
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08603582 |
Feb 20, 1996 |
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5810827 |
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08603582 |
Feb 20, 1996 |
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08300379 |
Sep 2, 1994 |
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5514139 |
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08603582 |
Feb 20, 1996 |
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08479363 |
Jun 7, 1995 |
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5643272 |
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08479363 |
Jun 7, 1995 |
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08342143 |
Nov 18, 1994 |
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5597379 |
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08342143 |
Nov 18, 1994 |
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08300379 |
Sep 2, 1994 |
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5514139 |
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Current U.S.
Class: |
606/87 |
Current CPC
Class: |
A61B 17/1767 20130101;
A61F 2/3859 20130101; A61B 17/155 20130101; A61B 2017/1602
20130101; A61B 17/157 20130101; A61B 17/1675 20130101; A61B 17/1764
20130101 |
Class at
Publication: |
606/087 |
International
Class: |
A61B 017/16 |
Claims
1-19. (canceled)
20. An apparatus for facilitating the selection of an orthopedic
prosthesis having a component with a bone engaging surface, an
oppositely disposed articulating surface and defining a component
spacing therebetween, said apparatus comprising: a first component
having an inwardly facing surface and an outwardly facing surface;
said inwardly facing surface having a first portion defining a
configuration substantially similar to a portion of the bone
engaging surface of the component and a second portion adapted for
placement facing a non-resected bone surface; and said outwardly
facing surface defining a first articulating surface at least
partially disposed opposite each of said first and second portions
of said inwardly facing surface and defining a spacing between said
outwardly facing surface and said first portion greater than said
component spacing.
21. The apparatus of claim 20, wherein said first component further
defines at least one guide element having a predefined position
relative to said first portion.
22. The apparatus of claim 20, further comprising a second
component mountable on a second bone and having a second bearing
surface engagable with said first articulating surface and a
mounting surface engagable with a resected bone surface, said first
and second components defining a mounting distance between said
first portion of said inwardly facing surface and said mounting
surface; said mounting distance being substantially equivalent to a
corresponding mounting distance occupied by the orthopedic
prosthesis.
23. The apparatus of claim 22, wherein said first component is
adapted for placement on a distal femur and said articulating
surface of said first component defines a single condylar-shaped
projection and said second component is adapted for placement on a
proximal tibia.
24. The apparatus of claim 20, wherein said inwardly facing surface
defines a volume greater than the volume defined by the bone
engaging surface of the orthopedic prosthesis.
25. An apparatus for facilitating the selection of an orthopedic
prosthesis having a component with a bone engaging surface defining
a plurality of intersecting planar surfaces, an oppositely disposed
articulating surface and defining a component spacing therebetween,
said apparatus comprising: a first component having an inwardly
facing surface and an outwardly facing surface; said inwardly
facing surface having a first portion defining a substantially
planar surface lying within a single plane and configured
substantially similar to a portion of the corresponding bone
engaging surface of the orthopedic prosthesis and a second portion
positionable proximate a non-resected bone surface and defining a
volume greater than the volume defined by the bone engaging surface
of the permanent prosthesis; and said outwardly facing surface
defining a first articulating surface at least partially disposed
opposite each of said first and second portions of said inwardly
facing surface and defining a spacing between said outwardly facing
surface and said first portion greater than the component
spacing.
26. The apparatus of claim 25, wherein said first component further
defines at least one guide element having a predefined position
relative to said first portion.
27. The apparatus of claim 26, wherein said at least one guide
element comprises an opening extending from said outwardly facing
surface to said first portion of said inwardly facing surface.
28. The apparatus of claim 25, further comprising a second
component mountable on a second bone and having a second bearing
surface engagable with said first articulating surface and a
mounting surface engagable with a resected bone surface, said first
and second components defining a mounting distance between said
first portion of said inwardly facing surface and said mounting
surface; said mounting distance being substantially equivalent to a
corresponding distance occupied by the orthopedic prosthesis.
29. The apparatus of claim 28, wherein said first component is
adapted for placement on a distal femur and said articulating
surface of said first component defines a single condylar-shaped
projection and said second component is adapted for placement on a
proximal tibia.
30. A method of implanting an orthopedic prosthesis at a joint
between a first bone and a second bone, said method comprising:
providing an apparatus and a corresponding prosthesis, said
prosthesis having first and second prosthesis components, said
first prosthesis component having a bone engaging surface and an
oppositely disposed articulating surface defining a component
spacing therebetween, said apparatus having a first apparatus
component having an inwardly facing surface and an outwardly facing
surface, said inwardly facing surface having a first portion
defining a configuration substantially similar to a portion of said
bone engaging surface and a second portion adapted for placement
facing a non-resected bone surface; partially preparing the first
bone to receive the prosthesis; mounting the first apparatus
component on the first bone wherein said outwardly facing surface
of said first apparatus component opposite said first portion of
said inwardly facing surface is spaced outwardly from the bone by a
distance which is greater than said prosthesis component spacing;
assessing the fit of said provisional prosthesis; and completing
the preparation of the first bone after assessing the fit of said
apparatus.
31. The method of claim 30 further comprising the step of at least
partially preparing the second bone to receive said prosthesis and
wherein said steps of partially preparing the first and second
bones defines a gap between first and second prepared surfaces
located respectively on the first and second bones and wherein said
step of assessing the fit of said apparatus includes assessing the
fit of said apparatus within the gap.
32. The method of claim 32 wherein said apparatus includes a second
apparatus component mountable on the second bone and having a
second bearing surface engagable with said outwardly facing surface
of said first apparatus component and a mounting surface engagable
with the second bone, said first and second apparatus components
defining a mounting distance between said first portion of said
inwardly facing surface of said first apparatus component and said
mounting surface of said second apparatus component, said mounting
distance being substantially equivalent to a corresponding mounting
distance occupied by the prosthesis and wherein assessing the fit
of said apparatus within the gap includes positioning said first
and second apparatus components to separate the first and second
bones by said mounting distance.
33-66. (canceled)
Description
RELATED APPLICATIONS
[0001] This application is a continuation of co-pending U.S.
application Ser. No. 09/799,325 filed Mar. 5, 2001, which is a
continuation-in-part of U.S. application Ser. No. 09/261,528, filed
Mar. 3, 1999, now U.S. Pat. No. 6,197,064, which was a continuation
of U.S. application Ser. No. 08/892,286, now U.S. Pat. No.
5,879,354, which was a divisional of U.S. application Ser. No.
08/649,465, filed May 17, 1996, now U.S. Pat. No. 5,755,803, which
was a continuation-in-part application of U.S. application Ser. No.
08/603,582, filed Feb. 20, 1996, now U.S. Pat. No. 5,810,827, which
was a continuation-in-part application of U.S. application Ser. No.
08/300,379, filed Sep. 2, 1994, now U.S. Pat. No. 5,514,139, dated
May 7, 1996, and which was also a continuation-in-part application
of U.S. application Ser. No. 08/479,363, now U.S. Pat. No.
5,643,272, which is a continuation-in-part of U.S. application Ser.
No. 08/342,143, filed Nov. 18, 1994, now U.S. Pat. No. 5,597,379,
which is a continuation-in-part application of U.S. application
Ser. No. 08/300,379, filed Sep. 2, 1994, now U.S. Pat. No.
5,514,139, dated May 7, 1996. U.S. Ser. No. 479,363. The entire
disclosures of these related applications are expressly
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention generally relates to methods and apparatus
for systems for preparing musculoskeletal structures to receive an
orthopedic implant.
[0004] 2. Related Art
[0005] Different methods and apparatus have been developed in the
past to enable a surgeon to remove bony material to create
specifically shaped surfaces in or on a bone for various reasons
including to allow for attachment of various devices or objects to
the bone. Keeping in mind that the ultimate goal of any surgical
procedure is to restore the body to normal function, it is critical
that the quality and orientation of the cut, as well as the quality
of fixation, and the location and orientation of objects or devices
attached to the bone, is sufficient to ensure proper healing of the
body, as well as appropriate mechanical function of the
musculoskeletal structure.
[0006] In total knee replacements, a series of planar and/or
curvilinear surfaces, or "resections," are created to allow for the
attachment of prosthetic or other devices to the femur, tibia
and/or patella. In the case of the femur, it is common to use the
central axis of the femur, the posterior and distal femoral
condyles, and/or the anterior distal femoral cortex as guides to
determine the location and orientation of distal femoral
resections. The location and orientation of these resections are
critical in that they dictate the final location and orientation of
the distal femoral implant. It is commonly thought that the
location and orientation of the distal femoral implant are critical
factors in the success or failure of the artificial knee joint.
Additionally, with any surgical procedure, time is critical, and
methods and apparatus that can save operating room time, are
valuable. Past efforts have not been successful in consistently
and/or properly locating and orienting distal femoral resections in
a quick and efficient manner.
[0007] The use of oscillating sawblade based resection systems has
been the standard in total knee replacement for over 30 years. Due
to their use of this sub-optimal cutting tool, the instrumentation
systems all possess certain limitations and liabilities.
[0008] Perhaps the most critical factor in the clinical success of
TKA is the accuracy of the implant's placement. This can be
described by the degrees of freedom associated with each implant;
for the femoral component these include location and orientation
that may be described as Varus-Valgus Alignment, Rotational
Alignment, Flexion-Extension Alignment, A-P location, Distal
Resection Depth Location, and Mediolateral Location. Conventional
instrumentation very often relies on the placement of 1/8 or
{fraction (3/16)} inch diameter pin or drill placement in the
anterior or distal faces of the femur for placement of cutting
guides. In the case of posterior referencing systems, the distal
resection cutting guide is positioned by drilling two long drill
bits into the anterior cortex. As these long drills contact the
oblique surface of the femur they very often deflect, following the
path of least resistance into the bone. As the alignment guides are
disconnected from these cutting guides, the drill pins will
"spring" to whatever position was dictated by their deflected
course thus changing their designated, desired alignment to
something less predictable and/or desirable. This kind of error is
further compounded by the "tolerance stacking," inherent in the use
of multiple alignment guides and cutting guides. Another error
inherent in these systems further adding to mal-alignment is
deflection of the oscillating sawblade during the cutting process.
The use of an oscillating sawblade is very skill intensive as the
blade will also follow the path of least resistance through the
bone and deflect in a manner creating variations in the cut
surfaces which further contribute to prosthesis mal-alignment as
well as poor fit between the prosthesis and the resection surfaces.
Despite the fact that the oscillating saw has been used in TKA for
more than 30 years, orthopedic salespeople still report incidences
where poor cuts result in significant gaps in the fit between the
implant and the bone.
[0009] It is an often repeated rule of thumb for orthopedic
surgeons that a "Well placed, but poorly designed implant will
perform well clinically, while a poorly placed, well designed
implant will perform poorly clinically." One of the primary goals
of the invention described herein is to eliminate errors of this
kind to create more reproducible, consistently excellent clinical
results in a manner that requires minimal manual skill on the part
of the surgeon.
[0010] None of the previous efforts of others disclose all of the
benefits and advantages of the present invention, nor do the
previous efforts of others teach or suggest all the elements of the
present invention.
OBJECTS AND SUMMARY OF THE INVENTION
[0011] Many of the specific applications of the method and
apparatus of the present invention described herein apply to total
knee replacement, a surgical procedure wherein planar surfaces
and/or curvilinear surfaces must be created in or on bone to allow
for proper attachment or implantation of prosthetic devices.
However, it should be noted that it is within the scope of the
present invention to apply the methods and apparatus herein
described to the removal of any kind of material from bones in any
other application where it is necessary, desirable or useful to
remove material from bones.
[0012] The apparatus of the present invention comprises a number of
components including a positioning apparatus, a pattern apparatus
and a cutting apparatus.
[0013] The pattern apparatus is oriented and located by the use of
the positioning apparatus which references the geometry of a bone
to be resected and/or other anatomic landmarks. When used to resect
a distal femur, the positioning apparatus also references the long
axis of the femur. Once the positioning apparatus has been properly
located, aligned, and initially fixed in place, the pattern
apparatus may be attached thereto, and then adjusted according to
the preferences of the surgeon utilizing the apparatus, and then
the pattern apparatus can be rigidly fixed to a bone to be
resected. This ensures the pattern apparatus is properly located
and oriented prior to the use of the cutting apparatus to remove
material from the bone.
[0014] More specifically, when the method and apparatus of the
present invention are used in connection with resecting a distal
femur, the positioning apparatus is located and aligned utilizing
the intramedullary canal of the femur, (thereby approximating the
long axis of the femur), the distal surfaces of the femoral
condyles, the anterior surface of the distal femur, and the
posterior surfaces of the femoral condyles, which are referenced to
indicate the appropriate location and orientation of the pattern
apparatus. Fixation means may be used to fix the positioning
apparatus, as well as the pattern apparatus to the distal femur.
Means may be present in the positioning apparatus and/or pattern
device for allowing the following additional adjustments in the
location and orientation of the pattern device:
[0015] 1. internal and external rotational adjustment;
[0016] 2. varus and valgus angular adjustment;
[0017] 3. anterior and posterior location adjustments;
[0018] 4. proximal and distal location adjustment; and
[0019] 5. flexion and extension angular adjustment.
[0020] Cannulated screws, fixation nails or other fixation means
may then be used to firmly fix the pattern apparatus to the distal
femur. The positioning apparatus may then be disconnected from the
pattern apparatus and removed from the distal femur. Thus, the
location and orientation of the pattern apparatus is
established.
[0021] The pattern device possesses slot-like features, or a
cutting path, having geometry that matches or relates to the
desired geometry of the cut. When used in connection with resecting
a knee, the cutting path resembles the interior profile of the
distal femoral prosthesis. The cutting path guides the cutting
apparatus to precisely and accurately remove material from the
distal femur. Thus, the distal femur is thereby properly prepared
to accept a properly aligned and located distal prosthesis.
[0022] In preparing a patella, the pattern device may be an
integral part of the positioning apparatus which is oriented and
located by referencing the geometry of the patella itself as well
as the structures of the patellofemoral mechanism to determine the
location and orientation of a predominantly planar resection. The
cutting device may then be employed to perform the resection of the
patella by traversing the path dictated by the pattern device, thus
dictating the final location and orientation of the patella
prosthesis.
[0023] The apparatus of the present invention comprises a number of
components including an ankle clamp, an alignment rod, a fixation
head, cutting guide clamps having an integral attachment mechanism,
and a milling bit.
[0024] The method of present invention includes the steps of
attaching the ankle clamp about the ankle, interconnecting the
distal end of the alignment rod with the ankle clamp,
interconnecting the fixation head with the proximal end of the
alignment rod, partially attaching the fixation head to the
proximal tibia, aligning the alignment rod, completely attaching
the fixation head to the proximal tibia, interconnecting the
cutting guide clamps with the alignment rod, positioning the
cutting guide clamps about the proximal tibia, securing the cutting
guide clamps to the tibia at a proper location, removing the
fixation head, and cutting the proximal tibia with the milling
bit.
[0025] The implant of the present invention has an outer bearing
surface and an inner attachment surface. The outer bearing surface
functions as a joint contact surface for the reconstructed bone.
The inner attachment surface contacts a bone and is attached
thereto. The inner attachment surface of the implant is curvilinear
from an anterior to a posterior area of the femur, as is
conventionally known, and is also curvilinear from a medial to a
lateral area of the femur to approximate the shape of natural
femur. The resection of the femur for accommodating the implant can
be properly performed by a milling device employing one or more
curvilinear milling bits.
[0026] There are numerous advantages associated with the
curvilinear implant of the present invention. First, it will allow
for a very thin implant cross-section and therefore necessitate the
removal of the least amount of viable osseous tissue. Accordingly,
the kinematics of the artificial joint could be made to be as close
as possible to that of a healthy, natural knee joint. In addition,
the curvilinear geometry of the implant dramatically decreases the
stress risers inherent in conventional rectilinear femoral implants
and allows for a thinner cross-sectional geometry while potentially
increasing the resistance of the implant to mechanical failure
under fatigue or impact loading. Conversely, the curvilinear
geometry of the implant may also allow for an advantageous
reduction in the flexural rigidity of the implant which may result
in avoidance of the "stress-shielding" inherent in rigid implant
designs.
[0027] This curvilinear implant of the present invention could also
result in a less expensive femoral implant because of the reduced
amount of material needed for the implant, as well as an improved,
more natural, and even stronger knee replacement. The cross-section
of the implant could be varied to assist in seating the implant and
to increase the strength and fit of the implant. The implants of
the present invention having curvilinear implant surfaces could be
fabricated of metal, plastic, or ceramic or any other material.
Further, the thickness of the implants and the material required to
fabricate the implant could be reduced as the implants are adapted
to increasingly curvilinear surfaces.
[0028] The resected surfaces of a femur or other bone to accept the
implant of the present invention could be prepared by the apparatus
and method for resection shown and described in the prior related
applications set forth herein, the entire disclosures of which are
expressly incorporated herein by reference.
[0029] The apparatus of the present invention comprises a number of
components including a positioning and drill guide, a cutting guide
and a cutting apparatus. The drill guide is used to create holes in
the medial and lateral sides of the femur that correspond to the
fixation features of the cutting guide. The cutting guide is
oriented and located by inserting fixation nubs connected to the
cutting guide into the medial and lateral holes in the femur. The
cutting guide can then be further affixed to the femur. The cutting
apparatus can then be used with the cutting guide to resect the
femur. A conventional cutting block used with a conventional
oscillating saw can also be positioned and interconnected with a
femur in a similar manner using the drill guide of the present
invention to create medial and lateral holes. A cutting guide can
then be attached to the holes. A conventional cutting block can be
interconnected with the cutting guide for attachment of the block
to the femur. This invention can also be used in connection with a
cortical milling system, i.e., a cutting system for providing a
curvilinear cutting path and curvilinear cutting profile. Likewise,
a tibial cutting guide can similarly be positioned on a tibia with
a drill guide.
[0030] It is a primary object of the present invention to provide
an apparatus for properly resecting the distal human femur.
[0031] It is also an object of this invention to provide an
apparatus for properly orienting a resection of the distal human
femur.
[0032] It is an additional object of the resection apparatus of the
present invention to properly locate the resection apparatus with
respect to the distal human femur.
[0033] It is even another object of the resection apparatus of the
present invention to properly orient the resection apparatus with
respect to the distal human femur.
[0034] It is another object of the resection apparatus of the
present invention to provide a guide device for establishing the
location and orientation of the resection apparatus with respect to
the distal human femur.
[0035] It is still a further object of the resection apparatus of
the present invention to lessen the chances of fatty embolisms.
[0036] It is even a further object of this invention is to provide
a resection apparatus capable of forming some or all of the
resected surfaces of the distal human femur.
[0037] It is another object of the resection apparatus of the
present invention to provide an apparatus which is simple in design
and precise and accurate in operation.
[0038] It is also an intention of the resection apparatus of the
present invention to provide a guide device for determining the
location of the long axis of the femur while lessening the chances
of fatty embolism.
[0039] It is also an object of the resection apparatus of the
present invention to provide a device to physically remove material
from the distal femur in a pattern dictated by the pattern
device.
[0040] It is even another object of the resection apparatus of the
present invention to provide a circular cutting blade for removing
bone from the distal human femur to resection the distal human
femur.
[0041] It is also an object of the present invention to provide a
method for easily and accurately resecting a distal human
femur.
[0042] These objects and others are met by the resection method and
apparatus of the present invention.
[0043] It is a primary object of the present invention to provide
methods and apparatus for femoral and tibial resection.
[0044] It is another object of the present invention to provide a
method and apparatus for properly, accurately and quickly resecting
a bone.
[0045] It is also an object of this invention to provide a method
and apparatus for properly orienting and locating a resection of a
bone.
[0046] It is a further object of the present invention to provide a
method and apparatus to properly locate and orient the resection
apparatus with respect to a bone.
[0047] It is another object of the present invention to provide
methods and apparatus for femoral and tibial resection which are
simple in design and precise and accurate in operation.
[0048] It is an additional object of the present invention to
provide a method and apparatus to physically remove material from a
bone in a pattern dictated by a pattern device and/or the geometry
of a cutting device.
[0049] It is a further object of the present invention to provide
methods and apparatus for resecting a bone which allows one to
visually inspect the location of the cut or cuts prior to making
the cut or cuts.
[0050] It is yet a further object of the present invention to
provide a method and apparatus for resecting a bone which
physically removes material from the bone along a surface dictated
by a guide device.
[0051] It is still a further object of the present invention to
provide a method and apparatus for resecting a bone which employs a
milling bit or form cutter for removing material from the bone.
[0052] It is a further object of the present invention to provide
methods and apparatus for femoral and tibial resection wherein the
apparatus can be located on a bone to be cut in a quick, safe and
accurate manner.
[0053] It is a primary object of the present invention to provide a
method and apparatus for properly resecting the proximal human
tibia in connection with knee replacement surgery.
[0054] It is also an object of the present invention to provide a
method and apparatus for resecting the proximal human tibia which
minimizes the skill necessary to complete the procedure.
[0055] It is another object of the present invention to provide a
method and apparatus for resecting the proximal human tibia which
properly orients the resection of the proximal tibia.
[0056] It is even another object of the present invention to
provide a method and apparatus for resecting the proximal human
tibia which is easy to use.
[0057] It is yet another object of the present invention to provide
a method and apparatus for resecting the proximal human tibia which
orients the resection in accordance with what is desired in the
art.
[0058] It is still yet another object of the present invention to
provide a method and apparatus for resecting the proximal human
tibia which minimizes the amount of bone cut.
[0059] It is a further object of the present invention to provide a
method and apparatus for resecting the proximal human tibia which
allows one to visually inspect the location of the cut prior to
making the cut.
[0060] It is even a further object of the present invention to
provide a method and apparatus for resecting the proximal human
tibia which is simple in design and precise and accurate in
operation.
[0061] It is yet a further object of the present invention to
provide a method and apparatus for resecting the proximal human
tibia which physically removes material from the proximal tibia
along a surface dictated by a guide device.
[0062] It is still a further object of the present invention to
provide a method and apparatus for resecting the proximal human
tibia which employs a milling bit for removing material from the
proximal tibia.
[0063] It is also an object of the present invention to provide a
method and apparatus for resecting the proximal human tibia which
includes a component which is operated, and looks and functions,
like pliers or clamps.
[0064] It is even another object of the present invention to
provide an alternate embodiment of the method and apparatus for
resecting the proximal human tibia which includes a component that
resembles a U-shaped device for placing about the tibia.
[0065] It is even a further object of the present invention to
provide an alternate embodiment of the method and apparatus for
resecting the proximal human tibia which includes a component that
resembles an adjustable, square, U-shaped device for placing about
the tibia.
[0066] These objects and others are met and accomplished by the
method and apparatus of the present invention for resecting the
proximal tibia.
[0067] It is a primary object of the present invention to provide a
method and apparatus for removing material from bones.
[0068] It is another object of the present invention to provide a
method and apparatus for properly resecting bone.
[0069] It is also an object of this invention to provide a method
and apparatus for properly orienting a resection of a bone.
[0070] It is a further object of the present invention to provide a
method and apparatus to properly orient the resection apparatus
with respect to a bone.
[0071] It is an additional object of the present invention to
provide a method and apparatus for properly locating a bone
resection.
[0072] It is a further object of the present invention to provide a
method and apparatus to properly locate the resection apparatus
with respect to a bone.
[0073] It is even another object of the resection apparatus of the
present invention to provide a guide device and method of use
thereof for establishing the location and orientation of the
resection apparatus with respect to a bone.
[0074] It is an additional object of the present invention to
provide a method and apparatus for making a curvilinear bone
resection.
[0075] It is still a further object of the resection apparatus of
the present invention to lessen the chances of fatty embolisms.
[0076] It is even further object of this invention to provide a
method and apparatus capable of forming or re-forming some or all
of the surfaces or resected surfaces of a bone.
[0077] It is another object of the present invention to provide a
method and apparatus which is simple in design and precise and
accurate in operation.
[0078] It is also an intention of the present invention to provide
a method and apparatus for determining the location of the long
axis of a bone while lessening the chances of fatty embolisms.
[0079] It is also an object of the present invention to provide a
method and apparatus to physically remove material from a bone in a
pattern.
[0080] It is an additional object of the present invention to
provide a method and apparatus to physically remove material from a
bone in a pattern dictated by a pattern device and/or the geometry
of a cutting device.
[0081] It is even another object of the resection apparatus of the
present invention to provide a cylindrical or semi-cylindrical
cutting device and method of use thereof for removing material from
a bone.
[0082] It is also an object of the present invention to provide a
method and apparatus for easily and accurately resecting a
bone.
[0083] It is also an object of the present invention to provide a
method and apparatus for resecting a bone which minimizes the
manual skill necessary to complete the procedure.
[0084] It is even another object of the present invention to
provide a method and apparatus for resecting a bone which is easy
to use.
[0085] It is still yet another object of the present invention to
provide a method and apparatus for resecting a bone which minimizes
the amount of bone removed.
[0086] It is a further object of the present invention to provide a
method and apparatus for resecting a bone which allows one to
visually inspect the location of the cut or cuts prior to making
the cut or cuts.
[0087] It is yet a further object of the present invention to
provide a method and apparatus for resecting a bone which
physically removes material from the bone along a surface dictated
by a guide device.
[0088] It is still a further object of the present invention to
provide a method and apparatus for resecting a bone which employs a
milling bit or form cutter for removing material from the bone.
[0089] It is even another object of the present invention to
provide a method and apparatus for removing material from a bone
such that both the cutting path and cutting profile are
predominantly curvilinear.
[0090] It is a primary object of the present invention to provide
an apparatus to properly replace damaged bony tissues.
[0091] It is also an object of this invention to provide an
apparatus to properly replace damaged bony tissues in joint
replacement surgery.
[0092] It is also an object of the present invention to provide an
implant for the attachment to a distal femur in the context of knee
replacement surgery.
[0093] It is an additional object of the present invention to
provide a method and apparatus for making a curvilinear
implant.
[0094] It is another object of the present invention to provide an
implant having a reduced thickness to reduce the amount of material
required to make the implant.
[0095] It is even another object of the present invention to
provide an implant having curvilinear fixation surfaces for
increasing the strength of the implant.
[0096] It is another object of the present invention to provide an
implant having a fixation surface that is anterior-posterior
curvilinear and mediolateral curvilinear.
[0097] It is another object of the present invention to provide an
implant that has a fixation surface that is shaped to resemble a
natural distal femur.
[0098] It is also an object of the present invention to provide an
implant apparatus for allowing proper patellofemoral
articulation.
[0099] It is a further object of the present invention to provide
for minimal stress shielding of living bone through reduction of
flexural rigidity.
[0100] It is an additional object of the present invention to
provide an implant apparatus having internal fixation surfaces
which allow for minimal bony material removal.
[0101] It is another object of the present invention to provide an
implant apparatus with internal fixation surfaces that minimize
stress risers.
[0102] It is another object of the present invention to provide an
implant apparatus having internal fixation surfaces for precise
fixation to curvilinear body resections.
[0103] It is another object of the present invention to provide an
implant apparatus having internal fixation surfaces for precise
apposition to curvilinear body resections.
[0104] It is another object of the present invention to provide an
implant apparatus having internal fixation surfaces for curvilinear
interior fixation geometries closely resembling the geometry of the
external or articular geometry of the implant apparatus.
[0105] It is also an object of this invention to provide a method
and apparatus for properly locating and orienting a prosthetic
implant with respect to a bone.
[0106] It is another object of the present invention to provide an
implant which is simple in design and precise and accurate in
operation.
[0107] It is also an object of the present invention to provide an
implant which minimizes the manual skill necessary to complete the
procedure.
[0108] It is still yet another object of the present invention to
provide an implant which minimizes the amount of bone removed.
[0109] It is even another object of the present invention to
provide a method and apparatus for removing material from a bone
such that both the cutting path and cutting profile are
predominantly curvilinear.
BRIEF DESCRIPTION OF THE DRAWINGS
[0110] Other important objects and features of the invention will
be apparent from the following detailed description of the
invention taken in connection with the accompanying drawings in
which:
[0111] FIG. 1. is an exploded view of the resection apparatus of
the present invention showing the positioning apparatus body, the
angular adjustment component and the rotational alignment
component.
[0112] FIG. 2 is a side plan view of the guide device of the
resection apparatus of FIG. 1 attached to a distal human femur.
[0113] FIG. 3 is an exploded view of the pattern device of the
resection apparatus of the present invention.
[0114] FIG. 4 is a side plan view of the resection apparatus shown
in FIG. 2 with the pattern device fixed to the distal human
femur.
[0115] FIG. 5 is an exploded front view of the cutting device of
the resection apparatus of the present invention.
[0116] FIG. 6 is a top plan view of the pattern device and the
cutting device of the resection apparatus of the present invention
affixed to the distal human femur.
[0117] FIG. 7 is a side plan view of an intermedullary rod having a
helical groove for use with the resection apparatus shown in FIG.
1.
[0118] FIG. 8 is a partially exploded side plan view of an
embodiment of the tibial resection apparatus of the present
invention shown attached to the tibia, wherein the cutting guide
clamps are of a fixed size and directly interconnect with the
alignment rod.
[0119] FIG. 9 is a top plan view of the tibial resection apparatus,
shown in FIG. 8 prior to insertion of the milling bit into the
apparatus.
[0120] FIG. 10 is a partially exploded side plan view of another
embodiment of the tibial resection apparatus shown in FIG. 8,
wherein the cutting guide clamps interconnect with the alignment
rod by means of a cutting guide clamp linkage.
[0121] FIG. 11 is a side plan view of an embodiment of the cutting
guide clamps shown in FIG. 8, wherein the cutting guide clamps are
adjustable.
[0122] FIG. 12 is a top plan view of the cutting guide clamps shown
in FIG. 11.
[0123] FIG. 13 is a perspective view of an embodiment of the tibial
resection apparatus shown in FIG. 8, showing the proximal tibial
referencing stylus attached to the cutting guide clamps.
[0124] FIG. 14 is a cross-sectional view of the profile of the ends
of the clamp members taken along line A-A in FIG. 12.
[0125] FIG. 15 is a cross-sectional view of the profile of the ends
of the cutting guides taken along line B-B in FIG. 12, the ends of
the clamps mating with the ends of the cutting guides for
positioning the cutting guides with respect to the clamps.
[0126] FIG. 16 is a perspective view of an alternate embodiment of
a U-shaped cutting guide for use in the present invention.
[0127] FIG. 17 is a top plan view of another alternate embodiment
of a square U-shaped cutting guide for use in the present
invention.
[0128] FIG. 18 is a perspective view of another alternate
embodiment of a partial cutting guide for use in the present
invention when the patellar tendon, patella, or quad tendon
interferes with placement of the cutting guide about the tibia.
[0129] FIG. 19 is a rear perspective view of an embodiment of the
pattern apparatus of the present invention.
[0130] FIG. 20 is a front perspective view of the pattern apparatus
shown in FIG. 19.
[0131] FIG. 21 is a partially exploded side plan view of the
positioning apparatus shown in FIG. 19.
[0132] FIG. 22 is an exploded perspective view of the cross-bar of
the pattern apparatus shown in FIG. 19.
[0133] FIG. 23 is a partially cut away side plan view of the
pattern plate/cross-bar attachment linkage for interconnecting the
pattern plate to the cross-bar as shown in FIG. 19.
[0134] FIG. 24 is a perspective view of the positioning apparatus
of the present invention.
[0135] FIG. 25 is a top plan view of the positioning apparatus
shown in FIG. 24.
[0136] FIG. 26 is an exploded perspective view of the positioning
apparatus shown in FIG. 24.
[0137] FIG. 27 is an exploded perspective view of the protractor
rod guide assembly portion of the positioning apparatus shown in
FIG. 24.
[0138] FIGS. 28A-28D are plan views of another embodiment of a rod
guide assembly for use with the positioning apparatus shown in FIG.
24.
[0139] FIG. 29 is a side plan view of an embodiment of the fixation
device for affixing the pattern apparatus shown in FIG. 19 to a
bone.
[0140] FIG. 30 is a partial side plan view of the pattern apparatus
shown in FIG. 19, showing the posterior/anterior referencing
guide.
[0141] FIG. 31 is a side plan view of another embodiment of the
pattern apparatus shown in FIG. 19.
[0142] FIG. 32 is a side plan view of another embodiment of the
positioning apparatus shown in FIG. 24 for use in performing
ligament balancing; FIGS. 32A and 32B are cross-sectional views
along section A-A in FIG. 32.
[0143] FIGS. 33A and B are front plan views of an embodiment of the
cutting apparatus of the present invention for cutting a bone a in
curvilinear cross-sectional plane.
[0144] FIG. 34 is a perspective view of a handle for guiding a
milling bit along a cutting path.
[0145] FIG. 35 is a perspective view of another embodiment of the
pattern apparatus shown in FIG. 19, having a milling bit engaged
therewith.
[0146] FIG. 36 is a side plan view of the pattern apparatus shown
in FIG. 35 with the milling bit disengaged from the pattern
apparatus.
[0147] FIG. 37 is another side plan view of the pattern apparatus
shown in FIG. 36 showing the milling bit engaged with the pattern
apparatus.
[0148] FIG. 38 is a perspective view of a femoral implant having a
curved implant bearing surface.
[0149] FIG. 39 is a side plan view of the femoral implant shown in
FIG. 38.
[0150] FIG. 40 is a side plan view of another embodiment of the
pattern apparatus and positioning apparatus of the present
invention for resecting a patella.
[0151] FIG. 41 is a top plan view of the patella resection
apparatus shown in FIG. 40.
[0152] FIG. 42 is a front plan view of the patella resection
apparatus shown in FIG. 40.
[0153] FIG. 43 is a perspective view of another embodiment of the
pattern apparatus of the present invention for cutting a bone.
[0154] FIG. 44 is a perspective view of another embodiment of the
alignment apparatus shown in FIG. 24.
[0155] FIG. 45 is a partially exploded side plan view of another
embodiment of the pattern apparatus of the present invention for
cutting a bone.
[0156] FIG. 46 is a partially exploded perspective view of the
interconnection of a handle with milling bit for use in connection
with pattern plate shown in FIG. 45.
[0157] FIG. 47 is front plan view of another cutting apparatus for
use in connection with the present invention.
[0158] FIG. 48 is a side plan view of the femoral implant shown in
FIG. 38, FIGS. 48A, 48B, 48C and 48D being sectional views taken
along lines A-A, B-B, C-C and D-D of FIG. 48, respectively.
[0159] FIG. 49 is a side plan view of the curvilinear milling bit
and resection guide shown in FIG. 35.
[0160] FIG. 50 is a side plan view of another embodiment of the
femoral implant shown in FIG. 38.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0161] As shown generally in FIGS. 1-6, the resecting apparatus of
the present invention comprises a number of components, namely
positioning apparatus generally indicated at 10 comprising
positioning body generally indicated at 12, angular adjustment
block generally indicated at 32, rotational alignment device
generally indicated at 50, pattern device generally indicated at 59
and cutting means generally indicated at 90.
[0162] As shown in detail in FIG. 1, the positioning apparatus,
generally indicated at 10, includes a positioning body generally
indicated at 12 having sides 13, top surface 14, front surface 15,
back surface 19 and cross member 18. Extending from a lower end of
the positioning body 12 is positioning tongue 20 having an upper
surface 22. Extending into the positioning body 12 from top surface
14 to the cross member 18 and through the front and back surfaces
15 and 19, is a gap generally defined by slots 16 and partial slot
walls 17. Sides 13 include apertures 24 for receiving locking
screws 25. Also extending through the body 12 from the back surface
19 to the front surface 15 are apertures 27 for receiving fixation
screws 26.
[0163] The positioning apparatus 10 receives and holds angular
adjustment block generally indicated at 32. Angular adjustment
block 32 includes a front surface 34 having wings 36 sized to be
received by the slots 16 in the positioning body 12 to hold the
angular adjustment block 32. The angular adjustment block 32 is
locked into place in the positioning body 12 by means of locking
screws 25, which extend through apertures 24 in the positioning
body 12 and contact the wings 36 of the angular adjustment block 32
to secure the angular adjustment block 32 to the positioning body
12. The angular adjustment block 32 establishes the angular
alignment and anterior/posterior location of the positioning
apparatus 10.
[0164] The angular adjustment block 32 also includes back surface
38 and an aperture 40 extending from the back surface 38 through
the angular adjustment block 32 to the front surface 34. The
aperture 40 receives an intermedullary rod 42 therethrough. The
intermedullary rod 42 comprises a shaft 43 and a handle 44. The
shaft 43 extends through the angular adjustment block 32 and into
the intermedullary canal which extends along the axis of the femur
to aid in establishing the orientation of the resection apparatus
of the present invention as hereinafter described.
[0165] The rotational alignment device, generally indicated at 50,
includes a shaft 51 having a groove 52 therealong and a block 53
having a back surface 54 and wings 56. The rotational alignment
device 50 is interconnected with the positioning body 12 by means
of the wings 56 received in slots 16 of the positioning body 12.
The rotational alignment device 50 may be secured to the
positioning body 12 by means of locking screws 25 which extend
through apertures 24 in the positioning body 12 to contact the
wings 56. The locking screws 25 may be made of various
configurations depending upon their specific function. Importantly,
the locking screws 25 are used to rigidly affix one component or
device to another to ensure that the relative locations and
orientations are maintained despite the rigors of surgery.
[0166] As shown in FIG. 2, wherein the positioning body 12 is
fitted with the angular adjustment block 32 and the rotational
alignment device 50, the entire positioning apparatus 10 is
connected to a human femur 7 by means of the shaft 43 of the
intermedullary rod 42. The shaft 43 extends through the angular
adjustment block 32, and thereby through the positioning body 12
into the intermedullary canal which extends along the axis of the
femur 7. The intermedullary rod 42, shown in FIG. 7, has a groove
41 transversing a helical path 45 along the axis of the shaft 43.
The groove 41 relieves intermedullary pressure that leads to fatty
embolisms. The basic concept of the intermedullary rod 42 with the
groove 41, is that as it is inserted into the femur, which contains
liquid fatty tissue, the liquid fatty tissue is drawn up the groove
41 of the intermedullary rod 42 to draw the fatty liquid tissue out
of the femur. Preferably, the intermedullary rod would have a
hexagonal head, (not shown) to permit it to be driven by a powered
device such as an electrical hand held tool. Importantly, the
groove 41 does not have a cutting edge, which would risk
perforation of the femoral cortex. Accordingly, the device does not
cut solid material, but removes liquid material from the
intermedullary canal. Therefore, the risk of fatty embolism is
reduced.
[0167] After positioning body 12 is properly located against the
femur 7 by means of the intermedullary rod 42 and the angular
adjustment block 32, fixation screws 26 may be advanced through the
apertures 27 in the positioning body 12 until they make contact
with the distal femoral condyles of the femur 7, and are then
driven into the distal femoral condyles of the femur 7 to initially
affix the positioning apparatus to the distal femur 7. It should be
noted that the fixation screws 26 may also be advanced and adjusted
to make up for deficiencies in the distal femoral condyles.
Accordingly, the positioning body 12 is positioned such that the
front surface 15 is put into contact with the distal femoral
condyles by direct contact, and the tongue 20 is positioned under
the femur 7 and in contact therewith.
[0168] As can be seen in FIG. 2, the shaft 51 of the rotational
alignment device 50 extends above the femur 7 and allows for
rotation of the pattern device 59, hereinafter described, about the
distal femur 7. Additionally, the rotational alignment device 50
allows for the anterior/posterior positioning of the pattern device
59 with respect to the femur 7. Importantly, the configurations of
the positioning body 12, the angular adjustment block 32 and the
rotational alignment device 50 are not limited to the structure set
forth herein, but may be of different shapes and may interconnect
in different ways. These components may even be formed as a unitary
or partially unitary device.
[0169] As shown in FIG. 3, the pattern device 59 includes pattern
plates 60 having tops 61, and cutting paths, generally indicated at
62, extending therethrough. The cutting paths 62 outline the
desired resection shape of the distal femur 7. Generally, the
cutting paths 62 could include a first vertical path 64, extending
to a first diagonal path 65, extending to a second diagonal path
66, extending to a second vertical path 67, extending to a third
diagonal path 68 and then extending to a horizontal path 69.
Alternatively, the cutting paths 62 could describe any desired
resection shape for the femur 7. The pattern plates 60 also include
locking screws 75 for interconnecting the pattern plates 60 with a
crossbar 80.
[0170] The pattern device 59 of the present invention preferably
includes two pattern plates 60 held in a spaced apart relationship
by crossbar 80. The crossbar 80 separates the pattern plates 60
sufficiently to permit the pattern plates 60 to extend along the
sides of the distal femur 7. The crossbar 80 includes a front
surface 82, back surface 84, a top surface 83, a central aperture
86 extending from the front surface 82 to the back surface 84, a
lock aperture 88 extending through the top surface 83, and a lock
screw 89. The central aperture 86 of the crossbar 80 receives the
shaft 51 of the rotational alignment device 50. Accordingly, the
pattern device 59 is interconnected with the positioning apparatus
10 so that the pattern device 59 is properly oriented with respect
to the femur 7. Upon proper positioning of the crossbar 80, with
respect to the shaft 51 of the rotational alignment device 50, lock
screw 89 is extended through lock aperture 88 to contact the shaft
51 to lock the crossbar 80 and, accordingly, the pattern device 59,
onto the shaft 51 of the rotational alignment device 50, and
accordingly, to positioning apparatus 10. This completed assembly
is attached to the femur 7, as shown in FIG. 4.
[0171] As additionally shown in FIGS. 3 and 4, the pattern plates
60 include plate apertures 72 for receiving cannulated screws 70
which have apertures extending therethrough for receiving fixation
nails 71 therethrough. Accordingly, after the pattern device 59 is
interconnected with the positioning apparatus 10, and properly
located and oriented with respect to the femur 7, the cannulated
screws 70 are extended through the plate aperture 72 to contact the
sides of the distal femur 7. Then, in order to fix the pattern
plates 60 with respect to the femur 7, the fixation nails 71 are
driven into the distal femur 7 to lock the pattern plate 60 into
position on the distal femur 7. The cannulated screws 70 have sharp
leading edges for allowing decisive purchase in the distal femur 7
before the introduction of the fixation nails 71 to complete
fixation of the pattern device 59 to the distal femur 7.
[0172] The pattern plates 60 by virtue of the cutting paths 62,
dictate the shape of the resection of the femur 7. The cutting
paths 62 are essentially channels through the pattern plates 60.
The cutting paths 62 receive the cutting device and guide it as it
resects the surface of the distal femur 7. The pattern plates 60
straddle the distal femur 7 mediolaterally and are suspended by the
crossbar 80. Likewise, crossbar 80 maintains the proper
relationship between the pattern plates 60 before and during the
resection of the distal femur 7. The location of the crossbar 80
and accordingly, the pattern plates 60, may be adjusted with
respect to the positioning apparatus 10 by adjusting the position
of the block 53 of the rotational alignment device 50 within the
slots 16 of the positioning body 12, and locking the same with
locking screws 25.
[0173] The cutting paths 62 in the pattern plates 60 receive and
guide the cutting device shown in FIG. 5 and generally indicated at
90. The cutting device 90 performs the actual cutting of the femur
7 to resect the femur 7. The cutting device may be of any known
configuration. In a preferred embodiment, the cutting device is a
drill. The drill 90 is generally cylindrical in shape and may
possess helical cutting teeth along its length to cut the femur 7.
The drill 90 includes a hexagonal end 95 to permit the use of an
electric powered drive, typically an electric drill. Further, the
drill 90 includes drill bushings 92 at the ends of the drill 90 to
provide a non-metallic bearing between the cutting paths 62 in the
pattern plates 60 to avoid galling and to ensure smooth
articulation of the drill 90 along the cutting path 62. Positioned
between the drill bushings 92 and the drill 90 are retention
springs 94 which are essentially coil springs retained within the
drill bushings 92 to allow the drill bushings 92 to be easily
attached and removed from the drill 90. These retention springs 94
are commercially available in medical grade stainless steels. The
drill bushings 92 retain the retention springs 94 which hold the
drill bushings 92 in position 92 on the drill 90 while allowing the
drill bushings 92 to rotate freely. The drill 90 may also include
circumferential grooves 91 for allowing attachment and retention of
the drill bushings 92 by means of the retention springs 94.
Importantly, the configuration of the drill 90 can vary in
accordance with what is known in the art, as long as the cutting
device can follow the cutting paths 62 in the pattern plates 60 to
resect the femur 7.
[0174] As shown in FIG. 6, after the pattern device 59 is attached
to the distal femur 7, and positioned accordingly by means of the
positioning apparatus 10, and secured to the distal femur 7 by
means of cannulated screws 70 and fixation nails 71, positioning
apparatus 10 may be removed from connection to the distal femur 7
leaving the pattern device 59 attached to the distal femur 7 to
permit resecting of the distal femur. The drill 90 is then
positioned within the cutting paths 62 between the pattern plates
60. Next the drill 90 is rotated by power means in connection with
the hexagonal end 95, and is then moved along the cutting path 62
to resect the distal femur 7. It should also be noted that the
cutting means could be operated by hand.
[0175] Instead of two pattern plates 60, a single pattern plate
could be employed if it is sufficiently sturdy to support and guide
the drill. The pattern plates 60 may also comprise plates having
edges in the shape of the desired distal femoral resection pattern.
Thus, the cutting device may be drawn along the edges of the
pattern plates to resect the distal femur. Further, any cutting
device that can be employed to follow the cutting paths in the
pattern plates is considered to be within the scope of this
invention.
[0176] The resection apparatus of the present invention, through
proper use as previously described, provides extremely accurate and
reproducible bone cuts. While the anterior and distal areas of the
femur will almost always be able to be prepared in this manner,
interference from soft tissue such as fat and ligaments may
prohibit satisfactory preparation of the posterior femur. The
preparation of any remaining femoral surfaces may be completed in
any manner known in the art after using the instrumentation of the
present invention.
[0177] As shown in FIGS. 8-13, the tibial resection apparatus of
the present invention includes a number of components, namely,
cutting guide clamps generally indicated at 210, cutting guides
generally indicated at 220, ankle clamp generally indicated at 250,
alignment rod generally indicated at 260, cutting guide clamp
linkage generally indicated at 270, fixation block generally
indicated at 280, proximal tibial referencing stylus generally
indicated at 290, and milling bit generally indicated at 255. It
should be noted that the cutting guides 220 may be formed
integrally with the cutting guide clamps 210 as shown in FIGS. 8
and 9, or as separate members as shown in FIGS. 11, 12 and 13.
Also, the cutting guides 220 may ride the alignment 260 as shown in
FIGS. 8 and 9, or they may interconnect with the alignment rod 260
by means of cutting guide clamp linkage 270, as shown in FIGS. 11,
12 and 13.
[0178] As shown in FIG. 8, the ankle clamp 250 is attached at or
just above the ankle and exterior to the skin. Any conventional
ankle clamp may be used to firmly engage the ankle, or to engage
the tibia above the ankle, to obtain a reference point for the
other components of the present invention.
[0179] The ankle clamp is interconnected with and locked into place
on the alignment rod 260 in any way known in the art. Preferably,
though not necessarily, the alignment rod 260 is vertically
adjustable with respect to the ankle clamp 250. This vertical
adjustment can be achieved at the ankle clamp 250, at the
interconnection of the ankle clamp 250 and the alignment rod 260,
or within the alignment rod 260 itself. As shown in FIG. 8, the
alignment rod includes a first lower end 262 having an aperture 263
extending vertically therein for telescopically receiving a second
upper end 265 of the alignment rod 260. A set screw 264 is provided
for fixing the upper end 265 with respect to the lower end 262.
[0180] The fixation block 280 is interconnected with an upper end
of the alignment rod 260 by means of an aperture 282 in the
fixation block 280 sized to receive the alignment rod 260
therethrough, or in any other manner known in the art. A set screw
284 may be provided to extend into the fixation block 280, through
set screw aperture 286 in fixation block 280, to contact the
alignment rod 260, to lock the fixation block 280 onto the
alignment rod 260. The fixation block 280 additionally includes
apertures extending vertically therethrough for receiving fixation
pins 288 for affixing the fixation block 280 to the proximal tibia
208.
[0181] In operation, the ankle clamp 250 is attached about the
ankle, or about the tibia just above the ankle, on the exterior of
the skin. The fixation block 280 is already interconnected with the
alignment rod 260. It is preliminarily positioned over the proximal
tibia 208, and one of the fixation pins 288 is driven into the
proximal tibia 208. Thereafter, the alignment rod 260 is adjusted
to establish proper varus/valgus alignment and flexion/extension
angulation as is conventionally known. Upon proper alignment of the
alignment rod 260, the other fixation pin 288 is driven into the
proximal tibia 208 to completely fix the fixation block 280 to the
proximal tibia 208 to lock in the proper alignment of the alignment
rod 260. Then, the fixation block 280 may be locked into position
on the alignment rod 260.
[0182] After properly aligning and locking in the alignment of the
alignment rod 260, the cutting guide clamps 210 and the cutting
guides 220 may be employed. The cutting guide clamps 210 are
interconnected with the alignment rod 260 by means of cutting guide
linkage 270. Alternatively, the cutting guide clamps 210 could
directly interconnect with the alignment rod 260 through apertures
in the cutting guide clamps 210, as shown in FIGS. 8 and 9. As
shown in FIG. 10, the cutting guide clamp linkage 270 comprises a
body 271 having an alignment rod aperture 272 for receiving and
riding the alignment rod 260 and a pivot locking set screw 274
which extends into the cutting guide clamp linkage 270 through set
screw aperture 275 for contacting the alignment rod 260 and locking
the cutting guide clamp linkage 270 with respect to the alignment
rod 260. It should be pointed out that it may be desirable for the
alignment rod 260 to have a flattened surface extending
longitudinally along the alignment rod 260 for co-acting with set
screw 274 for maintaining proper alignment between the cutting
guide clamp linkage 270 and the alignment rod 260.
[0183] The cutting guide clamp linkage 270 also includes a pivot
shaft 276 rigidly interconnected with the body 271 of the cutting
guide clamp linkage 270 by member 277 to position the pivot shaft
276 a distance away from the body 271 such that the cutting guide
clamps 210 can be interconnected with the pivot shaft 276 and can
be properly utilized without interfering with the body 271 of the
cutting guide clamp linkage 270.
[0184] After the alignment rod 260 is properly aligned and locked
into position, the cutting guide clamp linkage 270 is moved into
its approximate desired position at the proximal tibia 208. It
should be noted that the cutting guide clamp linkage 270 of present
invention is positioned on the alignment rod 260 at the beginning
of the procedure, prior to aligning the alignment rod 260, and
prior to interconnecting the fixation block 280 with the alignment
rod 260. However, it is within the scope of the present invention
to provide a cutting guide clamp linkage 270 which is attachable to
the alignment rod 260 after the alignment rod 260 has been aligned
and locked into position.
[0185] After the cutting guide clamp linkage 270 is preliminarily
approximately located, it is locked into place on the alignment rod
260. Thereafter, the cutting guide clamps 210 may be interconnected
with the pivot shaft 276 by means of corresponding pivot apertures
217 in the cutting guide clamps 210.
[0186] As shown in FIGS. 11 and 12, the cutting guide clamps 210
include opposing hand grips 212 for grasping and manipulating the
cutting guide clamps 210. Crossbar members 214 extend from the hand
grips 212 to clamp members 218. The crossbar members 214 cross over
each other at cross over point 215 whereat the crossbar members 214
have mating recessed portions 216 which function to maintain the
hand grips 212 in the same plane as the clamp members 218. At the
cross over point 215, the crossbar members 214 can pivot with
respect to each other such that movement of the hand grips 212
towards each other moves the clamp members 218 together, and
likewise, movement of the hand grip members 212 away from each
other serves to move the clamp members 218 apart in the same manner
as scissors or pliers. At the cross over point 215, the crossbar
members 214 have corresponding pivot apertures 217 for receiving
the pivot shaft 276 of the cutting guide clamp linkage 270. Thus,
the cutting guide clamps 210 pivot about the pivot shaft 276 of the
cutting guide clamp linkage 270. It should be noted that the
crossbar members 214 could be interconnected with each other by a
rivet or other means known in the art, or could be entirely
independent pieces which co-act as set forth above only upon being
seated on pivot shaft 276.
[0187] The clamp members 218 of the cutting guide clamps 210
include cutting guide adjustment screw apertures 219 at the far
ends thereof for receiving A-P adjustment screws 230 for adjustably
interconnecting the cutting guides 220 with the clamp members 218,
for adjustable movement in the direction shown by arrow C in FIG.
11. The clamp members 218 may be adjustably interconnected with the
cutting guides 220 in any way known in the art. In one embodiment,
the cutting guide adjustment screw apertures 218 are threaded and
the cutting guides 220 have corresponding elongated apertures 228
extending over a portion of the length thereof for receiving the
A-P adjustment screws at a desired location therealong. The A-P
adjustment screws include a head 231, a retaining head 232, and a
threaded shaft 234. When the cutting guides 220 are positioned
correctly with respect to the clamp members 218, the A-P adjustment
screws 230 are tightened down to lock the cutting guides 220 onto
the clamp members 218 by actuating the head 231 to turn down the
threaded shaft 234 with respect to the clamp member 218. Note the
retaining head 232 of the A-P adjustment screws prevent the shaft
234 from being backed off out of engagement with the clamp member
218.
[0188] As shown in FIGS. 14 and 15, respectively, the clamp members
218 are shaped with opposing interior edges having chamfers 238 and
the opposite exterior edges of the cutting guides 220 have mating
recesses 239, both of said profiles extending along the contacting
surfaces of the clamp members 218, as seen along line A-A in FIG.
12, and the cutting guides 220, as seen along line B-B in FIG. 12,
to maintain a proper planar alignment therebetween. It should of
course be noted that any other method known in the art may be
employed to maintain the clamp members 218 and the cutting guides
220 in alignment. Additionally, the cutting guides 220 may include
A-P adjustment screw recesses 237 for receiving the head 231 of the
A-P adjustment screw 230.
[0189] The cutting guides 220 further include tibia attachment
means for attaching the cutting guides 220 to the tibia 208. Any
known attachment means may be employed to attach the cutting guides
220 to the tibia 208. As shown in FIGS. 9 and 11, a preferred
attachment means for attaching the cutting guides 220 to the tibia
208 are pins 236 extending through pin apertures 227 in the cutting
guides 220. The pins 236 may be captured in the pin apertures 227,
or they may be entirely separate. Preferably, means exist on the
cutting guides 220 for preliminarily attaching the cutting guides
220 to the tibia 208 prior to pinning the cutting guides 220
thereto, so that after proper positioning of the cutting guides
220, the hand grips 212 can be actuated by squeezing the hand grips
212 together to contact the cutting guides 220 against the tibia
208 so that the cutting guides 220 are preliminarily attached to
the tibia 208. Such means may include a plurality of small pins
captured by the cutting guide 220, or any other suitable means.
After the preliminary attachment of the cutting guides 220 to the
tibia 208, final attachment may be made by attachment pins 236 or
by any other means known in the art.
[0190] The cutting guides 220, importantly, include cutting slots
222 which each comprise lower cutting slot guide surface 223 and
upper cutting slot retaining surface 225, as well as cutting slot
entrance and exit 224 at one end thereof and cutting slot end wall
226 at the other end thereof. The cutting slot 222 is of a length
sufficient to extend across the proximal tibia 208, at a desired
angle to the intermedullary canal, at the widest point of the
proximal tibia 208, to allow the entire upper surface of the
proximal tibia 208 to be cut. The cutting slot 222 is of a size
sufficient to receive a cylindrical milling bit 255 such as that
shown in FIG. 16 and described in U.S. Pat. No. 5,514,139, filed
Sep. 2, 1994 by Goldstein, et al. The milling bit 255 comprises
central cutting portion 257 having helical cutting teeth along its
length for cutting bone. The milling bit 255 further comprises
spindles 256 extending from the central cutting portion 257 for
supporting the central cutting portion 257.
[0191] The milling bit 255 is inserted into and received in the
cutting slot 222 through cutting slot entrance 224, along the
direction shown by arrow A in FIG. 16. Note that the cutting slot
entrance 224 may be of a wider slot area or an upturned portion of
the slot 222 or the milling bit 255 may merely be inserted and
removed from the slot 222 at an end thereof. The spindles 256
extend through and co-act with the lower cutting guide surface 223
and the upper retaining surface 225 of the cutting slot 222 to
guide the milling bit 255 along the cutting slot 222 to resect the
proximal tibia 208, along the direction shown by arrow B in FIG.
16. At an end of one or both of the spindles 256 is a means for
engaging the milling bit 255 with a drive means such as an electric
drill, or other drive means. This engagement means may include a
hexagonal head on one of the spindles, or any other suitable method
of engagement known in the art. Additionally, bushings may be
employed, either on the milling bit 255 or captured by the cutting
slot 222, to provide a non-metallic bearing between the spindles
256 of the milling bit 255 and the cutting slot 222 to avoid
galling and to ensure smooth articulation of the milling bit 255
along the cutting slots 222. Importantly, the configuration of the
milling bit 255 may be varied in accordance with what is known in
the art, as long as the cutting device can follow the cutting path
of the cutting slot to resect the proximal tibia. Additionally, it
should also be pointed out that other cutting tools may be used in
accordance with the present invention, including an oscillating or
reciprocating saw or other means for resecting the tibia by
following the cutting slots on the cutting guides.
[0192] After the cutting guide clamps 210 are preliminarily located
along the aligmnent rod 260, the cutting guides 220 are adjusted
with respect to the clamp members 218 for proper anterior-posterior
positioning to extend along the proximal tibia 208 for guiding the
milling bit 255. Importantly, the cutting slots 222 should extend
beyond the edges of the proximal tibia 208. Once proper
anterior-posterior alignment is obtained, the cutting guides 220
may be locked into place on the clamp members 218.
[0193] Thereafter, a proximal tibial referencing stylus 290 may be
attached to a referencing bracket 292 on the cutting guides 220.
The referencing bracket 292 may be positioned in any location on
the cutting guides 220, or on any other convenient component of the
tibia resection system of the present invention. Alternatively, the
referencing stylus 290 may be formed as part of a component of the
present invention, or as a separate component which could function
merely by contacting the cutting guides 220 of the present
invention or any other component thereof. The referencing stylus
290, shown in FIG. 13, includes stylus body 294 which may be
interconnected with the referencing bracket 292 in any manner known
in the art, preferably by a quick release and connect mechanism or
a threaded connection. The stylus body 294 supports a stylus arm
296, which is rotatable with respect to the stylus body 294 and
configured to extend out and down from the stylus body 294 to
contact the proximal tibia 208 at a tip 298 of the stylus arm 296.
The stylus body 294, arm 296 and tip 298 are sized to contact the
proximal tibia 208 to reference the positioning of the cutting
guides 220 to cut the proximal tibia at a proper distance below the
proximal tibia 208 as is known in the art. The stylus arm 296 may
include more than one tip 298, such other tips extending down from
the stylus body 294 in varying distances.
[0194] In operation, one determines the desired location of the
stylus tip 298, unlocks the cutting guide clamp linkage 270 to
permit the linkage 270 to move up and down the alignment rod 260,
and places the tip 298 on the lowest point of the proximal tibia
208 to reference the position of the cutting guides with respect to
the proximal tibia 208 and with respect to the alignment rod 260.
Thereafter, the cutting guide clamp linkage 270 is locked to the
alignment rod 260 to lock the cutting guides 220 into the proper
position on the alignment rod 260, and accordingly, into proper
position with respect to the proximal tibia 208. Thereafter, the
hand grips 212 are actuated to press the cutting guides 220 against
the proximal tibia 208 to preliminarily lock them into position on
the proximal tibia 208. Next, the cutting guides 220 are fixed to
the proximal tibia 208 by pins 236 or any other desired fixation
means. The fixation block 280 can then be removed from the proximal
tibia 208, and the proximal tibia 208 may be resected.
[0195] The cutting operation is similar to the cutting operation
set forth in U.S. Pat. No. 5,514,139, filed Sep. 2, 1994 by
Goldstein, et al. Essentially, the cutting operation comprises
inserting the milling bit 255 into the cutting guide slots 222
through the slot entrance/exit 224 to position the central cutting
portion 257 between the cutting guides 220, the spindles 256
extending through the cutting guide slots 222. After the milling
bit 255 is positioned, the drive means may be interconnected
therewith, actuated, and the milling bit 255 moved along the
cutting slots 222 to resect the proximal tibia 208.
[0196] It should be noted that a handle may be provided for
attachment to the spindle which is not driven so that such spindle
may be guided evenly through the cutting slots 222 to facilitate
the cutting procedure. Alternatively, a handle can be provided
which interconnects with both spindles to further facilitate
control of the milling bit 255 during the cutting procedure.
Additionally, the bushings that fit over the spindles 256 of
milling bit 255 and ride in the cutting slots 222 may be captured
in the ends of the handle and the milling bit received
therethrough.
[0197] Additionally, it should be pointed out that it is within the
scope of the present invention to modify the cutting slots 222 such
that the upper retaining surface is eliminated, and the milling bit
255 merely follows the lower cutting guide surface 223. With the
cylindrical milling bit 255 herein described, this is especially
viable as the milling bit 255 tends to pull down into the bone as
it is cutting, thereby primarily utilizing the lower cutting guide
surface 223 of the cutting guide 220.
[0198] As shown in FIGS. 16-18, various other embodiments of the
cutting guides are considered within the scope of the present
invention. The cutting guide 320 shown in FIG. 16 is of a generally
U-shaped configuration, having cutting guide slots 322, lower
cutting guide surface 323, upper retaining surface 325, pin
apertures 327 and alignment rod aperture 328. This cutting guide
320 is used in the same manner as the cutting guides hereinbefore
described, the differences being that the cutting guide 320
interconnects directly with the alignment rod and that various size
cutting guides must be provided to accommodate various sized
tibias.
[0199] Likewise, the cutting guide 320, shown in FIG. 17, operates
in the same manner as the cutting guide devices hereinbefore
described, but it does not include cutting guide clamps. The
cutting guide 320 includes cutting slots 322, and it interconnects
directly with alignment rod by means of aperture 328. The distance
between facing members 330 can be adjusted by moving base members
332 and 334 with respect to each other to size the cutting guide
320 for the tibia to be cut. Upon proper sizing, the base members
332 and 334 may be locked with respect to each other by set screw
336 or any other means known in the art.
[0200] FIG. 18 shows an embodiment of the cutting guide for use
when the patellar tendon, the patella, or the quad tendon
interferes with the placement of the other cutting guides of the
present invention. As shown in FIG. 18, the cutting guide 350 may
be directly interconnected with the alignment rod, and positioned
on the tibia as hereinbefore set forth. Basically, this embodiment
of the invention includes only one cutting guide. The cutting guide
350 and the cutting guide slot 322 may be wider than in the
previous embodiments to help stabilize the milling bit in
operation. In this embodiment, the milling bit may be first plunged
across the tibia, and then moved therealong. The milling bit may be
spring loaded to increase resistance as it is plunged through the
cutting guide to bias the bit against being plunged too far across
the tibia to cause damage to the tissue about the tibia.
Additionally, a support member, not shown, could be provided to
extend from the cutting guide 350, over and across the tibia to the
other side thereof where it could have a slot to capture the
milling bit and provide additional support thereto. The reference
numerals 338, 360 and 392 correspond to the reference numerals 238,
260 and 292 respectively.
[0201] As shown generally in FIGS. 19-23, the pattern apparatus of
the present invention, generally indicated at 430, comprises
pattern plates, generally indicated at 432, and crossbar apparatus,
generally indicated at 440.
[0202] Pattern Plates
[0203] Pattern plates 432 include fixation apertures 434 extending
therethrough for accepting fixation means, as will hereinafter be
described, for affixing the pattern plates 432 to a bone. The
pattern plates 432 further include a cutting path 436 for dictating
the path along which a bone is to be cut. As shown in FIGS. 19-23,
which are directed to an embodiment of the present invention for
resecting a distal femur, the cutting path 436 in the pattern
plates 432 matches the profile of a femoral component of a knee
prosthesis for resecting the femur to accept the femoral component
of the prosthesis. Importantly, as will hereinafter be described,
the cutting path 436 could be identical in size and shape to an
interior bearing surface of a femoral component of the knee
prosthesis, or could vary in size and shape in accordance with
alternative methods and apparatus used to perform the resection.
For example, the cutting path could be larger than the desired
resection, but a larger cutting tool could be used to arrive at a
resection of the desired the desired size.
[0204] In the embodiment of the present invention shown in FIG. 21,
the cutting path 436 includes an anterior end 436A, an anterior cut
portion 436B, an anterior chamfer portion 436C, a distal cut
portion 436D, a posterior chamfer portion 436E, a posterior cut
portion 436F, and a posterior end 436G. Alternatively, the cutting
path 436 could be of any desired shape in accordance with the
prosthesis systems of the various manufacturers of such prosthesis,
the desires of the surgeon utilizing the apparatus and/or the
application for which a bone is to be cut.
[0205] Although a single pattern plate 432 may be employed in
resecting a femur or other bone (and in some cases, i.e., a partial
femur resection, it may be preferable to employ a single pattern
plate 432), two pattern plates 432 are generally employed to co-act
with each other to support a cutting means on two sides of a bone
to be cut. In the case of resecting a femur, a preferred embodiment
of the present invention, as shown in FIGS. 19-21, comprises two
pattern plates 432 positioned on opposing sides of a femur. The
pattern plates 432 are interconnected with each other, and
maintained in proper alignment with respect to each other by a
crossbar apparatus generally indicated at 440, to straddle a bone.
The pattern plates 432 include crossbar apertures 438 for
interconnecting with the crossbar apparatus 440. The pattern plates
may also include crossbar slots 439 for permitting quick
connect/disconnect between the pattern plates 432 and the crossbar
apparatus 440. Of course, it should be noted that the pattern
plates 432 could interconnect with the crossbar in any other manner
known in the art, or especially with bone cutting applications
other than resecting the femur, the pattern plates 432 could be
used without a crossbar.
[0206] Crossbar Apparatus
[0207] The crossbar apparatus 440 includes a number of component
parts, namely, T-bar 442 having a top 444 and a stem 446
interconnected with and extending from the top 444 in the same
plane. The T-bar 442, shown in the figures, comprises a flat metal
member having a uniform rectangular cross-section through both the
top 444 and the stem 446. Three threaded lock apertures 448 are
formed through the T-bar 442, one at each end of the top 444 and at
the far end of the stem 446. Lock screws 450, having gripable heads
452 and shafts 454 with threaded waists 456, threadably engage the
threaded lock apertures 448 in the T-bar 442. The lock screws 450
further include pin holes 458 extending radially through the shafts
454 at the terminal ends thereof for receiving pins 459 for
capturing the lock screws 450 on the T-bar 442.
[0208] The crossbar apparatus 440 further includes linkages 460
having a first end for interconnection with the T-bar 442 and a
second end for supporting and engaging pattern plates 432. The
first ends of the linkage 460 include a lower flat surface 462 for
contacting the T-bar 442, overhanging shoulders 464 for contacting
the sides of the T-bar 442, and an upper flat surface 466 for
contact with the lock screws 450 for locking the linkages 460 onto
the T-bar 442. As shown in detail in FIG. 23, the second ends of
the linkage 460 include cylindrical supports 468 for supporting the
pattern plates 432 thereon. The cylindrical supports 468 include
axial extending apertures 469 for receiving capture pins 470
therethrough, the capture pins 470 including flanged ends 472 and
threaded ends 474. The capture pins 470 serve to capture pattern
lock nuts 476 on the linkages 460, the capture pins 470 extending
through the axial apertures 469, the flanged ends 472 retaining the
capture pins 470 therein, the threaded ends 474 extending out of
the cylindrical supports 469 and into the threaded interior 477 of
the pattern lock nuts 476. The cylindrical supports 468 receive the
crossbar apertures 438 of the pattern plates 432 and the pattern
lock nuts 476 are threaded down onto the capture pins 470 to secure
the pattern plates 432 to the crossbar apparatus 440. Of course,
other embodiments of the crossbar apparatus sufficient for
supporting the pattern plates of the present invention are
considered within the scope of the present invention.
[0209] Positioning Apparatus
[0210] As shown in FIGS. 24-28, the positioning apparatus of the
present invention is generally indicated at 510. The positioning
apparatus generally comprises positioning body 520 and alignment
apparatus 580. The positioning body 520 comprises a frame 522
having sides 524, bottom 526 and top 528 arranged to form a frame
having a rectangular aperture defined therewithin. The top 528
further includes a head 530 formed thereon having a linkage
aperture 532 extending therethrough at an upper end thereof, and
having a lock aperture 534 extending from the upper edge of the
head to the linkage aperture 532. A lock screw 536 having a
threaded shaft 538 extends into and is threadably engaged with the
lock aperture 534 for locking the head 530 to a linkage, namely
crossbar linkage 540. Crossbar linkage 540 includes a first end
having an upper flat surface 542 for interconnecting with the
crossbar in a manner similar to the pattern plate linkages for
attaching the pattern plates to the crossbar as hereinbefore
described. The crossbar linkage 540 further includes a shaft 544
which is received by the linkage aperture 532 in the head 530 to
interconnect the positioning body 520 with the crossbar linkage 540
and hence with the crossbar apparatus 440 and the pattern apparatus
430. The positioning body can then be locked onto the crossbar
linkage 540 by means of lock screw 536.
[0211] The end of shaft 544 of the crossbar linkage 540 includes
projections 546 extending axially from the shaft 544. When the
shaft 544 is positioned in the linkage aperture 532, the
projections 546 extend beyond the frame 522 and are received in
slots 556 in alignment indicator 550 for keying the orientation of
the alignment indicator 550 with the alignment of the crossbar
linkage 540, and hence with the alignment of the crossbar apparatus
440 and the pattern apparatus 430. The alignment indicator 550
includes an alignment arrow 552 for indicating alignment on a scale
that may be set forth on the positioning body 520. An indicator pin
558 having a shaft 559 may be employed to pin the alignment
indicator 550 to the crossbar linkage 540.
[0212] Attachable to the bottom 526 of the positioning body 520 is
skid 560. The skid 560 includes skid apertures 562, one of which
may include an aperture flat 564 for ensuring proper alignment and
positioning of the skid 560 with respect to the positioning body
520. The skid 560 is attached to the bottom 526 of the positioning
body 520 by means of skid bolts 566 having threaded shafts 568
which co-act with threaded apertures in the bottom 526 of the
positioning body 520. Of course, the skids could be formed
integrally as part of the positioning body.
[0213] The sides 524 of the positioning body 520 include slots 570
extending in a facing relationship along the sides 524. The slots
extend from exterior surfaces of the sides to interior surfaces
thereof, i.e., to the interior rectangular aperture formed within
the positioning body 520.
[0214] Alignment Apparatus
[0215] The alignment apparatus 580 interconnects with the
positioning body 520 by means of alignment guide body 582 which is
a U-shaped member having sides 584 and a bottom 586. The alignment
guide body 582 is sized to fit within the rectangular aperture
formed within the positioning body 520. The alignment guide body
582 is retained within the positioning body by means of guide studs
572 that extend through the sides 524 of the positioning body 520
within the slots 570 and into guide apertures 588 at one side of
the alignment guide body 582. At the other side of the alignment
guide body 582 a lock stud 584 extends through the slot 570 in the
side 524 of the positioning body 520 and into a threaded lock
aperture 589 in the alignment guide body 582. The guide studs 572
and the lock stud 574 co-act to maintain the alignment guide body
582 within the positioning body 520, and the lock stud 574 can be
threaded down to lock the vertical position of the alignment guide
body 582 with respect to the positioning body 520.
[0216] At upper ends 590 of the sides 584 of the alignment guide
body 582 are plate apertures 591. The alignment plate 592 includes
bolt apertures 595 aligned with the plate apertures 591 of the
alignment guide body 582, and plate bolts 594 extend through the
bolt apertures 595 in the alignment plate 592 and into the plate
apertures 591 to secure the alignment plate 592 to the alignment
guide body 582. The alignment plate 592 further includes rod guide
aperture 597 which receives rod guide bolt 596 therethrough to
interconnect the alignment plate 592 with the IM rod guide 610 as
will hereinafter be described. Additionally, the alignment plate
592 includes lock slot 606 extending through the alignment plate
592 along an arc for purposes hereinafter described.
[0217] The IM rod guide 610 includes IM rod aperture 612 for
receiving an IM rod therethrough. The IM rod guide 610 is
interconnected at a forward end with the alignment plate 592 by
means of plate attachment aperture 614 on the rod guide 610 which
receives rod guide bolt 596 therein, after such bolt 596 passes
through the alignment plate 592 to secure the rod guide 610 in a
pivoting relationship with respect the alignment plate 592 at
forward ends of the rod guide 610 and the alignment plate 592. The
IM rod guide 610 is additionally interconnected with the alignment
plate 592 by rod guide lock bolt 600 which includes a threaded
shaft 210 and pin aperture 602. The rod guide lock bolt 600 extends
through the slot 606 in the alignment plate 592 and through
threaded lock bolt aperture 616 in the rod guide 610 where it is
captured by means of capture pin 618 extending through the pin
aperture 602. The IM rod guide further includes rod guide handle
620 which is configured to be easily manipulated.
[0218] The alignment plate 592 further includes a printed angular
rotation scale which indicates the degree of angular rotation
between the rod guide 620 and the alignment apparatus, and hence,
the angular rotation between the IM rod and the positioning body
520. After such alignment is determined, it can be locked into
place by tightening down rod guide lock bolt 600. Thereafter, with
such angular rotation fixed, the pattern apparatus 430 can be
positioned with respect to the bone to cut, and the positioning
apparatus 510 can be removed from interconnection with the IM rod
and the pattern apparatus 430, the IM rod removed from the bone,
and bone cutting can be initiated.
[0219] In another embodiment, as shown in FIGS. 28A, 28B, 28C and
28D, IM rod guide block 630 is used instead of the alignment plate
592 and the alignment guide body 582. The IM rod guide block 630
includes a rear surface 632, a front surface 634, a top surface 636
and sides 638. The sides 638 include retaining flanges 640 at the
rear and front surfaces for retaining the IM rod guide block 630
within the rectangular aperture formed by the positioning body 520.
The IM rod guide block 630 further includes IM rod aperture 642
extending through the block 630 from the rear surface 632 to the
front surface 634 for accepting the IM rod therethrough. The rod
aperture 642 extends through the guide block 630 at an angle A with
respect to axis of the guide block for accommodating the
varus/valgus orientation of the femur. The guide block 630 is part
of a set of blocks having rod apertures of various angles extending
therethrough, i.e., 5, 7, 9, 11, 13 degrees, for use with femurs
having varying angles of orientation. The guide block 630 also
includes lock aperture 646 for locking the proper vertical position
of the guide block 630 with respect to the positioning body 620.
The guide block 630 may additionally include two apertures 644 for
accepting an anterior referencing arm for use in determining the
anterior/posterior size of the femur. It should be noted that other
alignment means for aligning the positioning apparatus with respect
to a bone to be cut are considered within the scope of the present
invention.
[0220] Fixation Means
[0221] Various fixation means, including those known in the art,
can be used to fix the pattern plate or plates to the femur or
other bone to be cut. FIG. 29 shows a preferred fixation means,
generally indicated at 660. The fixation means 660 includes a spike
plate 664 carrying on one side thereof a spike or spikes 662 for
contacting, and even extending into, bone 661. At the other side of
the spike plate 664 is spike plate socket 666 for receiving plate
driving ball 668 in a keyed relationship therewith. The driving
ball 668 is interconnected to an end of driving sleeve 670 and
which has a threaded aperture extending therein from the opposite
end thereof.
[0222] A driving screw 672 having a threaded shaft 674 co-acts with
the internally threaded driving sleeve 670 such that the rotation
of the driving screw 672 either propels or retracts the driving
sleeve 670, as well as the spike or spikes 662, with respect to the
driving screw 672. The driving screw 672 further includes a
captured head 678 and capture flange 676. The captured head 678 is
received within a fixation aperture 434 in the pattern plate 432,
the capture flange 676 preventing the captured head 678 from
passing through the fixation aperture 434. A driving cap 680 is
interconnected with the captured head 678 at the outside of the
pattern plate 432. The driving cap 680 includes a shaft 682
received by the captured head 678, a flanged head 684 for
contacting against the outside of the pattern plate 432, and a
driver recess 686 of any desirable configuration for receiving
driving means such as a flat, phillips or hex head driving means
for driving the driving cap 680 to drive the driving screw 672 to
move the spike or spikes 662 towards or away from a bone.
[0223] Importantly, this type of fixation means allows for fixation
of the pattern plates 432 to even osteoporotic bones. Additionally,
this fixation means is self-adjusting to fit changing contours of
bones. Further, because of its relatively low profile, this
fixation means does not interfere with soft tissue about a bone to
be cut. Other types of fixation means include cannulated screws,
pins, spring loaded screws, captured screws, spiked screws and/or
combinations thereof, all of which are considered within the scope
of the present invention and could be used in connection with the
present invention.
[0224] Anterior/Posterior Referencing
[0225] The apparatus of the present invention further includes
built-in anterior/posterior referencing means as shown in FIG. 30
for use in connection with preparation of the distal femur in total
knee replacement. As is known in the art, anterior/posterior
referencing refers to proper positioning of the distal femur cuts
with respect to the anterior and/or posterior sides of the femur or
other bone to be cut.
[0226] The anterior/posterior difference between femoral implant
sizes may vary by as much as 3 to 5 millimeters between sizes. Of
course, many femurs are between sizes. Disregarding proper
positioning of the cutting guide and the associated femur cuts
could lead to flexion contracture (where the bone is slightly below
size and the implant adds too much material to posterior side of
femur which results in the inability to move the knee into flexion
because the extra posterior material contacts the tibial implant
components) and/or anterior notching of the femur (where the bone
is slightly above size and the anterior runout point of the
anterior cut is recessed in the anterior side of the bone in a
sharp notch, thus seriously weakening the structural integrity of
the distal femur, especially under cyclic fatigue or impact loading
conditions).
[0227] Anterior referencing systems have a major advantage over
posterior referencing systems in that they theoretically never
notch the anterior cortex of the femur. The drawback of anterior
referencing is that a slightly larger bone results in collateral
ligament laxity in flexion and a slightly smaller bone will result
in collateral ligament tightening in flexion (flexion
contracture).
[0228] Posterior referencing systems have a major advantage over
anterior referencing systems in that they theoretically never
develop flexion contracture. The drawback is that a slightly large
femur is prone to anterior notching, which can increase the
likelihood of distal femoral fractures under either impact loading
or cyclic fatigue loading.
[0229] Another approach to anterior/posterior referencing is a
hybrid design that allows for both anterior and posterior
referencing. The positioning apparatus 510 references the posterior
femoral condyles (posterior referencing), while the pattern plates
432 allow for precise referencing of the anterior femoral cortex.
The anterior referencing device can be as simple as that shown in
FIG. 30, wherein a referencing pin 694 is placed through the
anterior-most cutting paths 436 of the pattern plates 432 to
contact the anterior femoral cortex 661. The pattern plates 432
include markings S (smaller size) and L (larger size). When the pin
694 falls between the S and L marks, the pattern plates 432 are the
proper size and are properly positioned for that femur. If the pin
694 falls outside the range marked by S and L towards the S side, a
smaller size pattern plate should be used, and conversely, if the
pin 694 falls outside the range on the L side, a larger size
pattern plate should be used. Alternatively, the pattern plate 432
could be adjusted vertically via means not shown to compensate for
between-size bones.
[0230] In another embodiment, the pattern plate could include a
plunger assembly at the anterior end of the cutting path. The
plunger could be movable vertically to contact the femur and
indicate size of the femur with respect to the pattern plate in
use. As such, the plunger could be incrementally marked from +4 to
-4 millimeters with 0 being the proper size for the pattern plates
in use. Again, the pattern plates could be sized up or down if the
femur is off of the scale, or the pattern plates could be moved up
or down to compensate for between size bones depending upon surgeon
preference. If, for example, a bone registers a +2, anterior
notching of the femur would occur. To avoid this, the pattern
plates could be moved anteriorally 1 millimeter to +1. In this
manner, anterior notching would be minimized and the posterior
femoral condyles would only lack 1 millimeter of material, which
should not be detrimental as some ligamentous laxity in flexion is
acceptable because the collateral ligaments are normally slightly
looser in flexion than they are in extension. It should be noted
that the radii or curve in the anterior-most area of the cutting
path will assure that anterior notching is easily avoidable.
[0231] Pattern Plate with Tracking Means
[0232] Another embodiment of the pattern plates of the present
invention is shown in FIG. 31. In this embodiment, the pattern
plates, generally indicated at 710, basically comprise only the
lower edge, or bearing surface 716 of the cutting path 436 of
pattern plates 432 shown in FIGS. 19-21. Accordingly, the pattern
plate 710 includes fixation apertures 712 and crossbar aperture
714. The milling apparatus bears against the bearing surface and
follows the same therealong to resect the bone in accordance with
the shape of the bearing surface 716. Of course, the bearing
surface could be smaller or larger than the desired cut location
depending on the size of the milling apparatus. The pattern plate
710 could further include a groove or guide means 718 extending in
the pattern plate alongside the bearing surface and the milling
apparatus could include an arm or other retaining linkage 717
extending from the handle or bushing of the milling apparatus and
into the groove 718 for engagement with the groove 718 for guiding
or retaining the milling apparatus along the bearing surface 716 of
the pattern plate 710. Alternatively, it should be noted that the
bearing surface could also comprise just the upper surface of the
cutting path 436 of the pattern plates 432, as shown in FIGS.
19-21.
[0233] Ligament Balancing
[0234] As shown in FIG. 32, an alternative embodiment of the
alignment guide body 730 can be used for performing ligament
balancing. The alignment guide body 730 of this embodiment can
include a skid 732 formed as a part of the guide body 730, or
attachable thereto. The skid 732 is of a relatively thick
cross-section, approaching or equal to the cross-section of the
guide body 730. The guide body 730 is attached to the femur 661 and
the femur may be moved from extension to flexion and back, while
the ligament tension of the collateral ligaments is reviewed.
Ligamentous release can be performed to balance the ligaments.
Further, shims 736, in either a rectangular cross-section (FIG.
32A) or an angled cross-section (FIG. 32B), can be used in
connection with the alignment guide body 830 and skid 732. These
shims could be positioned between the underside of the skid 732 and
the resected tibia.
[0235] Milling Means
[0236] In a preferred embodiment of the invention, a cylindrical
milling bit is used for following the cutting path described in the
pattern plates for resecting a bone. Importantly, it is within the
scope of the present invention to use a flat reciprocating bit,
much like a hacksaw, for following the cutting paths described in
the pattern plates for resecting a bone.
[0237] Further, it may be desirable to make all or some of the cuts
using a cylindrical milling bit or a flat reciprocating bit having
a smooth center section without cutting means. An advantage of a
cutting tool without cutting means along a center portion thereof
is the protection of posterior cruciate ligament during resection
of the femur. Accordingly, one cutting tool could be used to make
the anterior cut, the anterior chamfer, the distal cut and the
posterior chamfer, while another cutting tool, with a smooth center
portion, could be used to make the posterior cut to avoid any
chance of jeopardizing the posterior cruciate ligament.
[0238] Additionally, the milling bits herein described can be used
with or without a guide handle as will hereinafter be described.
Further, it should be pointed out that it is within the scope of
the present invention to fabricate the milling bit or other cutting
tool from metal as heretofore known, or to alternatively fabricate
the milling bit or other cutting tool from a ceramic material. An
advantage of a ceramic milling bit or cutting tool is that such
resists wear and, accordingly would be a non-disposable component
of the present invention which would help to reduce the cost of the
system of the present invention.
[0239] Three Dimensional Shaping
[0240] Initially, it should be noted that the term cutting profile
the profile geometry of a mediolateral section taken normal to the
cutting path through the bony surfaces created by cutting the bone.
As shown in FIG. 33, in an alternate embodiment of the present
invention, a milling apparatus having a three-dimensional profile,
or a form cutter, can be used to shape a bone in three-dimensions.
The curved profile milling bit 750, like the milling bits used in
the previous embodiments of the present invention, includes cutting
teeth 752 along the length thereof and spindles 754 at the ends
thereof. This milling bit 730 can follow a pattern described by
pattern plates and can be guided with a handle as will be
hereinafter described.
[0241] Importantly, by using a milling bit having a curved profile,
one can cut a femur to resemble the natural shape of the femur,
i.e., the resected femur would include condylar bulges and a
central notch. This would reduce the amount of bony material that
must be removed from the femur while maintaining the structural
integrity of the femur. Of course, any prosthetic implant used for
attachment to a femur resected by the curved profile milling bit
would necessarily have an appropriately contoured inner fixation
surface for mating with contoured surface of the femur.
Additionally, it should be noted that the curved profile milling
bit could have one or more curvilinear bulges along the length
thereof, as shown in FIG. 33, or alternatively, could have one or
more bulges discretely formed along the length thereof as shown in
FIG. 35.
[0242] Guide Handle
[0243] As shown in FIG. 34, a guide handle, generally indicated at
698 may be used to guide the milling bit along the cutting path of
the pattern plate. The guide handle 698 comprises a grip portion
700 which is grasped by the user for manipulating the guide handle
698 and accordingly, the milling bit. The grip portion 700 is
interconnected with a crossbar member 702 which includes a
extension member 703 telescopically interconnected therewith. The
crossbar member 702 and the extension member 703 may be positioned
perpendicular with respect to grip portion 700. The extension
member 703 is telescopically movable in and out of crossbar member
702. Means may be provided for locking the relative position of the
extension with respect to the crossbar. Also, it should be noted
that the grip portion may rigidly or pivotally be interconnected
with the crossbar as desired.
[0244] Extending from outer ends of the crossbar 702 and the
extension member 703 are sidebars 704 in facing and parallel
relationship. The sidebars 704 have two ends, the first of which
are interconnected with the crossbar and the extension member, and
the second of which are configured to receive and capture spindles
or bushings of a milling bit in spindle bushings 706. The spindle
bushings are positioned in a facing relation and could include
captured bushings. The captured bushings receive the spindles of a
milling bit. The captured bushings are sized to be received by the
cutting path in the pattern plates and co-act therewith to guide a
milling bit therealong. Accordingly, after the pattern plate or
plates are attached to a bone, the milling bit is placed into the
cutting path. Next a milling handle 698 is positioned such the
spindle bushings are aligned with the spindles of the milling bit.
Next, the extension is actuated to retract into the crossbar to
move the spindle bushings onto the spindles of the milling bit
where they are captured. Next, the spindle bushings are positioned
within the cutting path of a pattern plate or plates. If necessary,
the extension and crossbar can be locked down to lock the entire
apparatus. Next, the milling bit is actuated and the grip portion
of the handle is grasped and manipulated to move the milling bit
along the cutting path to cut a bone.
[0245] Distally Positioned Pattern Plate
[0246] As shown in FIGS. 35-37, in an alternate embodiment of the
present invention for resecting a femur, the plates could take the
form of a rail assembly, generally indicated at 760, positioned
distally of the distal femur 661. The plates could be affixed to
the femur by fixation arms 762, attached at one or more points to
the rail assembly 760, and including fixation apertures 764 for
receiving fixation screws or other fixation means for attaching the
fixation arms 762, and hence the rail assembly 760, to a distal
femur 661. The rail assembly 760 includes one or more guide rails
766 which match the shape of the desired resection, though the
rails may be larger or smaller depending on the dimensions of the
milling apparatus used and the positioning of the assembly 760 with
respect to the femur. In the case that the assembly 760 includes
two guide rails 766, as shown, an end rail 768 may be used to
interconnect such guide rails 766. The end rail 768 could be
replaced by a connection means similar to the crossbar apparatus
440, hereinbefore described. The rail assembly may be positioned on
the distal femur in accordance with the teachings contained herein,
or in any other manner known in the art. After alignment, according
to any means disclosed herein or known or developed, and after
fixation of the assembly to a femur, a milling bit 770 may be used
to follow the guide rails 766 to resect the femur 661, the guide
spindles 772, or bushings (not shown), of the milling bit 770,
contacting and riding the guide rails 766. Importantly, the rail
assembly 760 is attached to a femur and used in much the same way
as the pattern plates previously described with the exception that
the rail assembly can be positioned substantially distal of the
femur, thereby potentially requiring less exposure and possibly
resulting in less interference for placement thereof. The rail
assembly 760 could further include an upper retaining rail for
forming a slot or cutting path for capturing the milling bit
therein. Additionally, it should be noted that any milling bit
described herein could be used with rail assembly 760 including a
curved profile milling bit.
[0247] Curvilinear Implants
[0248] As shown in FIGS. 38 and 39, an implant 780 may have
curvilinear interior surfaces 782, as well as a more conventional
curvilinear exterior surface. The particular example cited herein
is a femoral implant used in total knee arthroplasty but the
principles described herein may be applied to any application where
foreign or indigenous material is affixed to an anatomic feature.
The curvilinear bone surfaces necessary for proper fixation of such
an implant may be generated through the use of the curvilinear
milling or form cutter and the curvilinear cutting path means
discussed herein. While it is possible to use multiple form cutters
with differing geometries and, therefore, an implant with an
internal geometry that varies along the cutting path from the
anterior to the posterior of a femur, for the sake of
intraoperative time savings a single form cutter is preferable.
[0249] The mediolateral cross-sectional internal geometry of such
an implant, and therefore the necessary resected bony surfaces of
the femur, are consistent about the cutting path in a single form
cutter system. It should be noted that the implant may possess a
notch between members 784 (posterior femoral implant condyles) in
the areas approximately in between the distal and posterior femoral
condylar areas to accommodate the posterior cruciate ligament and
other factors. Because of the notch between the posterior femoral
condyles it may not be necessary for the form cutter to cut any
material in the notch. It may be desirable to provide outer flat
surfaces 785 with an adjoining curvilinear surface 782 positioned
therebetween. Other combinations of flat or curvilinear surfaces
are also within the scope of the present invention.
[0250] Additionally, it may be advantageous to utilize a secondary
form cutter as shown in FIG. 47 for use in creating a slot or slots
in or near the distal area of the femur after it has been resected.
Such a secondary cutter 790 would include engagement means 792 for
engagement with driving means, and a shaft 794 carrying cutters 796
for cutting slots into the femur through one or more of the
resected surfaces thereof. Through the inclusion of an additional
or adjunct cutting path in the pattern means, it would be
advantageous to utilize the form cutter to create the
aforementioned slots to accommodate the fixation fins which may be
molded as an integral part of the interior surface of the implant.
These fins would provide mediolateral fixation stability in
addition to that provided by the trochlear groove geometry of the
implant. Further, the fins also provide for additional surface area
for bony contact and ingrowth to increase implant fixation both in
cemented and cementless total knee arthroplasty.
[0251] There are numerous advantages to the femoral component
herein described. Foremost, it will allow for the thinnest implant
cross-section possible (perhaps 3 mm to 6 mm in thickness) and
therefore necessitate the removal of the least amount of viable
osseous tissue. This is especially critical in situations where the
probability of revision surgery is high and the amount of viable
bone available for revision implant fixation and apposition is a
significant factor in the viability of the revision procedure.
Since the form cutter configuration allows for similar amounts of
tissue to be removed from the trochlear groove, the bony
prominences surrounding the trochlear groove, the femoral condyles,
and the other articular surfaces of the femur, the external
geometry of the femoral implant can be optimized for patellofemoral
articulation as well as tibiofemoral articulation. In essence, the
kinematics of the artificial joint could be made to be as close as
possible to that of a healthy, natural knee joint. In addition, the
curvilinear geometry of the implant dramatically decreases the
stress risers inherent in conventional rectilinear femoral implants
and allows for a thinner cross-sectional geometry while potentially
increasing the resistance of the implant to mechanical failure
under fatigue or impact loading. Conversely, the curvilinear
geometry of the implant may also allow for an advantageous
reduction in the flexural rigidity of the implant which may result
in avoidance of the "stress-shielding" inherent in rigid implant
designs. Stress shielding being a phenomenon that may occur when
living bony tissue is prevented from experiencing the stresses
necessary to stimulate its growth by the presence of a stiff
implant. This phenomenon is analogous to the atrophy of muscle
tissue when the muscle is not used, i.e., when a cast is placed on
a person's arm the muscles in that arm gradually weaken for lack of
use.
[0252] Additionally, the curvilinear implant design may allow for
the use of a ceramic material in its construction. Since ceramics
are generally relatively weak in tension, existing ceramic implant
designs contain very thick cross-sections which require a great
deal of bony material removal to allow for proper implantation.
Utilization of ceramics in the curvilinear implant will not only
allow for the superior surface properties of ceramic, but also
avoid the excessively thick cross-sections currently required for
the use of the material.
[0253] This could result in a less expensive femoral implant
because of the reduced amount of material needed for the implant,
as well as an improved, more natural, and even stronger knee
replacement. It may be desirable to vary the cross-section of the
implant 780 to assist in seating the implant and to increase the
strength and fit of the implant. The implants of the present
invention having curvilinear implant surfaces could be fabricated
of metal, plastic, or ceramic or any other material. Further, the
thickness of the implants and the material required to fabricate
the implant could be reduced as the implants are adapted to
increasingly curvilinear surfaces. Also, it should be pointed out
the such implants with curvilinear implant surfaces require less
bone to be removed to obtain a fit between the implant and the
bone. Finally, it should be noted that curvilinear milling bits
hereinbefore described would work well for preparing a bone to
receive an implant with curvilinear interior implant surface.
[0254] Patella Shaping
[0255] The apparatus for preparing a patella, as shown in FIGS.
40-42, comprises a plier-like patella resection apparatus generally
indicated at 800. The patella resection apparatus 800 includes grip
handles 802 for manipulating the apparatus, cross-over members 804
pivotally interconnected with each other by pin 806, and patella
clamp members 808 extending from the cross-over members in parallel
and facing relation. The patella clamp members 808 have beveled
edges 810 for contacting and supporting a patella along the outer
edges thereof. Guide member structures 812 are mounted on each of
the patella clamp members 808 to form a retainer for a cutting
means to follow a cutting path defined by the upper surface of the
clamp members. Bushings 814 are captured within the retainer and
the cutting path for receiving a cutting means 816 and guiding the
cutting means 816 along the cutting path.
[0256] In preparing the patella, the pattern device may be an
integral part of the positioning apparatus which is oriented and
located by referencing the geometry of the patella itself as well
as the structures of the patellofemoral mechanism to determine the
location and orientation of a predominantly planar resection. The
cutting device may then be employed to perform the resection of the
patella by traversing the path dictated by the pattern device, thus
dictating the final location and orientation of the patella
prosthesis.
[0257] Bone Substitution and Shaping
[0258] Referring now to FIG. 43, another embodiment of the pattern
apparatus of the present invention for cutting bone is shown. This
embodiment of the invention includes pattern plates 832 having
cutting paths 836 described therein. The pattern plates 832 may be
positioned on a bone 828 having a tumor or other pathology 829
associated therewith. The pattern plates 832 may be interconnected
by crossbars 838 with opposing pattern plates (not shown)
positioned on the opposite side of the bone 828. Further, each set
of pattern plates 832 could be interconnected by means of
positioning rod 839 extending between the crossbars 838 to maintain
the relative location and orientation between the sets of pattern
plates 832. The pattern plates can be positioned along the bone in
accordance with what is known in the art, disclosed herein or
hereafter developed. After the pattern plates are properly
positioned, they can be affixed to the bone 828 with fixation means
extending through fixation apertures 834. After the pattern plates
are properly located and affixed to the bone, cutting can commence
by traversing a cutting means along the cutting paths 836 of the
pattern plates 832. By this step, the tumor or other pathology 829
can be cut from the bone 828 and a bone graft or other surgical
procedure can be implemented to repair and/or replace the bone that
has been cut. The benefits of cutting a bone with the pattern
plates of the present invention include providing smooth and even
cuts to the bone to facilitate fixation of bone grafts or other
means for repairing and/or replacing bone. Further, the same
pattern plates can be used to cut another identical sized and
shaped bone for grafting to the first bone to replace the cut away
bone.
[0259] Alternate Positioning and Alignment Guide
[0260] An alternate positioning and alignment guide is generally
indicated at 840 in FIG. 44. The positioning body 840 comprises a
crossbar linkage 842 and an alignment indicator 844 at an upper end
thereof for interconnecting with a crossbar to align pattern plates
interconnected with such crossbar. The positioning body 840 also
includes an alignment block 846 for interconnecting with an
intramedullary rod in much the same manner as the IM rod guide
block shown in FIG. 28. The alignment block 846 is vertically
movable along the positioning body 840 and can be locked into a
desired position by means of lock screw 860 which bears against a
flange 848 of the alignment block 846. The positioning body 840
further includes skids 850 for contacting the posterior surface of
the distal femoral condyles for referencing same.
[0261] Unicondylar and/or Single Pattern Plate Support
[0262] As shown in FIGS. 45 and 46, one pattern plate of the
present invention can be used by itself to guide a cutting means
along a cutting path to cut a bone. Such an application is
particularly useful for unicondylar resecting of a femur. Use of a
single pattern plate 862 is facilitated by bushing 868 having an
outer flange 870 with a bearing surface 872 and an internal bore
874 sized to receive a spindle 865 of a cutting tool therein. The
bushing 868 is sized to fit into the cutting path 864 of the
pattern plate 862, the bearing surface 872 of the flange 870
contacting the side of the pattern plate 862. Washer 876 includes a
central bore 878 sized to receive the far end of the bushing 868
extending past the pattern plate 862, the washer bearing against
the side of the pattern plate 862 opposite the side that the
bearing surface 872 of the flange 870 of the bushing 868 bears
against. Thus, the washer and the bushing co-act to form a stable
link with a pattern plate. As shown in FIG. 46, this link can be
fortified by means of bearing arms 880 interconnected with the
bushing and the washer, or formed integrally as part thereof, which
by pressure means are forced together to retain the bushing within
the cutting path of the pattern plate. After the bushing is
captured within the cutting path, the spindle of the cutting means
can be inserted through the bushing and interconnected with means
866 for driving the cutting means. Alternatively, it should be
pointed out that when using a single pattern plate to cut a bone,
it may be desirable to support the cutting means at the pattern
plate and also at the other end thereof. One could effect such
desired support at the other end of the cutting means by a brace or
other linkage interconnecting the other end of the cutting means
with a secondary support or anchor means positioned on the opposite
side of the bone or at another location.
[0263] Revisions
[0264] Conventional revisions require removal of the old implant
and the referencing of uncertain landmarks. Revisions, by means of
the present invention, allow for reference of the implant while it
is still on the bone. One can obtain varus/valgus referencing,
distal resection depth, posterior resection depth and rotational
alignment by referencing the geometry of the implant with the
alignment guide. An extramedullary alignment rod can be used to
facilitate flexion/extension alignment. The fixation screws can
then be advanced to touch the bone and mark their location by
passing standard drill bits or pins through the cannulations in the
fixation screws and into the bone. Then, the pattern and guide
device are removed, the old implant removed, and the pattern device
repositioned by means of the marked location of the fixation screws
and then fixed into place. Accordingly, the cuts for the new
implant, and thus the new implant itself, are located and
orientated based off of the old implant. This results in increased
precision and awareness of the final implant location and
orientation as well as potential intraoperative time savings.
[0265] The particular example of the present invention discussed
herein relates to a prosthetic implant for attachment to a femur in
the context of total knee arthroplasty, i.e., a femoral implant.
However, it should be pointed out that the principles described
herein may be applied to any other applications where foreign or
indigenous material is affixed to any other anatomic feature.
[0266] As shown generally in FIGS. 38 and 48, the implant apparatus
of the present invention, generally indicated at 910, comprises
curvilinear interior fixation surface 920 as well as curvilinear
exterior bearing surface 940. Importantly, the implant of the
present invention includes curvilinear surfaces extending from an
anterior to a posterior area of the femur and/or implant, as is
conventionally known, as well as curvilinear surfaces extending
from a medial to a lateral area of the femur and/or implant to
approximate the shape of natural femur. In other words, the
fixation path (i.e., corresponding to the cutting path along which
the milling bit rides to resect the femur; indicated by arrow A in
FIG. 38) as well as the fixation profile (as one proceeds along the
cutting profile orthogonally to the cutting path; indicated by
arrow B in FIG. 38) are both predominantly curvilinear. As such,
the cutting profile (arrow B) of the interior fixation surface 920
could include a curved or flat area 922 and another curved or flat
area 924 therebetween. Preferably, the outer areas 922 are flat or
relatively flat and the inner area 924 is curved to approximate the
shape of a natural distal femur 912. It should be pointed out that
the outer areas 922 could be curved, and the inner area 924 could
also be curved, but embodying differing radii of curvature.
Additionally, it should be pointed out that the geometry of the
internal fixation surface 920 of the implant 910 could be varied as
desired. As such, any combination of flat surfaces and curvilinear
surfaces could be used. As shown in FIG. 48, and in more detail in
FIGS. 48A, 48B, 48C and 48D, the cross-sectional thickness and
mediolateral width of the implant of the present invention could
vary along the implant 910. This variance results from merging a
cutting tool to cut a bone, i.e., the implant 910 closely resembles
in size and shape the material removed from the bone. Accordingly,
the cut starts as a point 925 and grows in depth and width.
[0267] The curvilinear bone surfaces necessary for proper fixation
of such an implant 910 may be generated through the use of the
curvilinear milling bit or form cutter and the curvilinear cutting
path means discussed in the previous related applications set forth
herein, the entire disclosures of which are expressly incorporated
herein by reference. Basically, the milling bit has a profile
resulting in form cutter configuration which is concentric about
its longitudinal axis to effect a curvilinear cutting profile for
receiving the implant of the present invention. One embodiment of
such a form cutter is shown in FIGS. 35 and 49. While it is
possible to use multiple form cutters with differing geometries and
therefore an implant 910 with an internal geometry that varies
along the cutting path from the anterior to the posterior of a
femur, for the sake of intraoperative time savings, a single
anatomically optimal form cutter is preferable.
[0268] The form cutter shown in FIGS. 35 and 49 comprises a cutting
guide 950 having cutting paths 952 interconnected by member 954. A
milling bit 960 having cylindrical milling areas 962 at the ends,
and a curved milling area 964 at the center could be used. Of
course, the milling areas carry cutting teeth. Spindles 961
interconnected at each end of the milling bit 960 could engage and
ride the cutting path 952 of the cutting guide 950. The milling bit
960 is then guided along the cutting path 952 by means of a handle.
Importantly, the shape of the milling bit 960 could be varied as
desired to create a resection having a desired cutting path as well
as a desired cutting profile.
[0269] The mediolateral cross-sectional internal geometry of such
an implant 910, and therefore the necessary resected bony surfaces
of the femur, are consistent about the cutting path in a single
form cutter system. It should be noted that the implant 910 may
possess a notch 970 between members 972 (posterior femoral implant
condyles) in the areas approximately between the distal and
posterior femoral condylar areas to accommodate the posterior
cruciate ligament, as well as for other reasons. Because of the
notch 970 between the posterior femoral condyles, the form cutter
may not cut any material in the notch 970.
[0270] Additionally, it may be advantageous to utilize a secondary
form cutter as shown in FIG. 47 for use in creating a slot or slots
in or near the distal area of the femur before or after it has been
resected. Such a secondary cutter 790 would include engagement
means 792 for engagement with driving means, and a shaft 794
carrying one or more cutters 796 for cutting slots into the femur
through one or more of the resected surfaces thereof.
[0271] Through the inclusion of an additional or adjunct cutting
path in the pattern means, it would be advantageous to utilize the
form cutter to create the aforementioned slots in the distal femur
to accommodate the fixation fins which may be molded as an integral
part of the interior surface of the implant 910. An implant with
fixation fins is shown in FIG. 50. The fins 980 would provide
mediolateral fixation stability in addition to that provided by the
trochlear groove geometry of the implant 910. Further, the fins
also provide for additional surface area for bony contact and
ingrowth to increase implant fixation both in cemented and
cementless total knee arthroplasty.
[0272] FIG. 33b shows another embodiment of a milling bit,
generally indicated at 754 for creating a curvilinear cutting path
and curvilinear cutting profile in femur 756. In this embodiment,
the transition from a first cutting area 984 to a second cutting
area 986 is continuous and smooth. This milling bit 754 also
includes spindles 981 at the ends thereof for engagement with
pattern means to guide the milling bit along a cutting path.
[0273] There are numerous advantages to the femoral component
herein described. Foremost, it will allow for the thinnest implant
cross-section possible (perhaps 3 mm to 6 mm in nominal thickness)
and therefore necessitate the removal of the least amount of viable
osseous tissue. This is especially critical in situations where the
probability of revision surgery is high and the amount of viable
bone available for revision implant fixation and apposition is a
significant factor in the viability of the revision procedure.
Since the form cutter configuration allows for similar amounts of
tissue to be removed from the trochlear groove, the bony
prominences surrounding the trochlear groove, the femoral condyles,
and the other articular surfaces of the femur, the external
geometry of the femoral implant can be optimized for patellofemoral
articulation as well as tibiofemoral articulation. In essence, the
kinematics of the artificial joint could be made to be as close as
possible to that of a healthy, natural knee joint.
[0274] In addition, the curvilinear geometry of the implant
dramatically decreases the stress risers inherent in conventional
rectilinear femoral implants and allows for a thinner
cross-sectional geometry while potentially increasing the
resistance of the implant to mechanical failure under fatigue or
impact loading. The implant could have a relatively consistent
cross-sectional thickness throughout the implant, or it could be
varied as desired.
[0275] The curvilinear geometry of the implant may also allow for
an advantageous reduction in the flexural rigidity of the implant
which may result in avoidance of the "stress-shielding" inherent in
rigid implant designs. Stress shielding being a phenomenon that may
occur when living bony tissue is prevented from experiencing the
stresses necessary to stimulate its growth by the presence of a
stiff implant. This phenomenon is analogous to the atrophy of
muscle tissue when the muscle is not used, i.e., when a cast is
placed on a person's arm the muscles in that arm gradually weaken
for lack of use.
[0276] Further, the curvilinear implant of the present invention
could allow for the use of a ceramic material in its construction.
Since ceramics are generally relatively weak in tension, existing
ceramic implant designs contain very thick cross-sections which
require a great deal of bony material removal to allow for proper
implantation. Utilization of ceramics in the curvilinear implant
would not only allow for the superior surface properties of
ceramic, but also avoid the excessively thick cross-sections
currently required for the use of the material.
[0277] The curvilinear implant of the present invention could
result in a less expensive femoral implant because of the reduced
amount of material needed for the implant, as well as an improved,
more natural, and even stronger knee replacement. It may desirable
to vary the cross-section of the implant to assist in seating the
implant, to increase the joint kinematics and to increase the
strength and fit of the implant. The implant of the present
invention could be fabricated of metal, plastic, or ceramic or any
other material or combination thereof. Further, the thickness of
the implants and the material required to fabricate the implant
could be reduced as the implants are adapted to increasingly
curvilinear surfaces. Also, it should be pointed out that such
implants with curvilinear implant surfaces require less bone to be
removed to obtain a fit between the implant and the bone. Finally,
it should be noted that curvilinear milling bits hereinbefore
described would work well for preparing a bone to receive an
implant with curvilinear interior implant surface.
[0278] Importantly, by using a milling bit having a curved profile,
one can cut a femur to resemble the natural shape of the femur,
i.e., the resected femur would include condylar bulges and a
central notch. This would reduce the amount of bony material that
must be removed from the femur while maintaining the structural
integrity of the femur. Of course, any prosthetic implant used for
attachment to a femur resected by the curved profile milling bit
would necessarily have an appropriately contoured inner fixation
surface for mating with contoured surface of the femur.
Additionally, it should be noted that the curved profile milling
bit could have one or more curvilinear bulges along the length
thereof, as shown in FIGS. 35 and 49, or alternatively, could have
one or more bulges discretely formed along the length thereof.
[0279] The complete disclosures of the patents, patent applications
and publications cited herein are incorporated by reference in
their entirety as if each were individually incorporated. Various
modifications and alterations to this invention will become
apparent to those skilled in the art without departing from the
scope and spirit of this invention. It should be understood that
this invention is not intended to be unduly limited by the
illustrative embodiments and examples set forth herein and that
such examples and embodiments are presented by way of example only
with the scope of the invention intended to be limited only by the
claims set forth herein.
* * * * *