U.S. patent application number 11/075553 was filed with the patent office on 2006-02-09 for methods and apparatus for improved profile based resection.
Invention is credited to Timothy G. Haines.
Application Number | 20060030855 11/075553 |
Document ID | / |
Family ID | 35717493 |
Filed Date | 2006-02-09 |
United States Patent
Application |
20060030855 |
Kind Code |
A1 |
Haines; Timothy G. |
February 9, 2006 |
Methods and apparatus for improved profile based resection
Abstract
Alignment guides, cutting guides, cutting tools and soft tissue
management techniques for profile based resection (PBR)
arthroplasty facilitate intraoperative and postoperative efficacy
and ease of use. In one embodiment, a manual alignment guide is
provided that permits less invasive incisions by providing soft
tissue accommodating contours or reliefs. In another embodiment, a
single medial drill guide plate is used for the PBR
arthroplasty.
Inventors: |
Haines; Timothy G.;
(Seattle, WA) |
Correspondence
Address: |
PATTERSON, THUENTE, SKAAR & CHRISTENSEN, P.A.
4800 IDS CENTER
80 SOUTH 8TH STREET
MINNEAPOLIS
MN
55402-2100
US
|
Family ID: |
35717493 |
Appl. No.: |
11/075553 |
Filed: |
March 8, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60551160 |
Mar 8, 2004 |
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60551080 |
Mar 8, 2004 |
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60551078 |
Mar 8, 2004 |
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60551096 |
Mar 8, 2004 |
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60551631 |
Mar 8, 2004 |
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60551307 |
Mar 8, 2004 |
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60551262 |
Mar 8, 2004 |
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Current U.S.
Class: |
606/88 |
Current CPC
Class: |
A61B 90/10 20160201;
A61F 2/3859 20130101; A61F 2002/3895 20130101; A61F 2310/00011
20130101; A61F 2002/30649 20130101; A61B 17/1764 20130101; A61F
2/38 20130101; A61B 17/1757 20130101; A61B 2017/1602 20130101; A61B
17/1671 20130101; A61B 17/1675 20130101 |
Class at
Publication: |
606/088 |
International
Class: |
A61B 17/58 20060101
A61B017/58 |
Claims
1. A method for implanting an orthopedic prosthesis during knee
artroplasty surgery comprising: providing a femoral prosthesis
having a fixation surface facing the femur and an articulation
surface adapted to articulate with a surface associated with the
tibia; positioning opposing guide patterns along opposing sides of
a distal portion of the femur, the guide patterns possessing
cutting tool guide surfaces geometrically corresponding to the
geometry of the fixation surface of the femoral prosthesis; fixing
the opposing guide patterns in position relative to the femur;
positioning a cutting tool mediolaterally between the femur and the
tibia; engaging the cutting tool with the cutting tool guide
surfaces; manipulating the tibia through a range of motion about
the femur while actuating the cutting tool to cut the femur to form
a resected surface for the femoral prosthesis; and operably
attaching the fernoral prosethesis to the resected surface.
2. The method of claim 1, wherein the wherein the cutting tool
further comprises a pair of soft tissue protective sleeves, each
soft tissue sleeve surrounding the cutting tool proximate a soft
tissue region associated with a respective side of the femur,
wherein the soft tissue protective sleeves are biased to track
along a contour of a side of the bone and prevent the cutting
profile from being exposed to the soft tissue region during the
step of manipulating the tibia through a range of motion about the
femur while actuating the cutting tool.
3. A method for implanting an orthopedic prosthesis during knee
arthroplasty surgery comprising: providing a femoral prosthesis
having a fixation surface facing the femur and an articulation
surface adapted to articulate with a surface associated with the
tibia; positioning a medial guide pattern along a medial side of a
distal portion of the femur, the guide pattern possessing cutting
tool guide surfaces geometrically corresponding to the geometry of
the fixation surface of the femoral prosthesis; fixing tie medial
guide pattern in position relative to the femur; positioning a
cutting tool mediolaterally between the femur and the tibia;
engaging the cutting tool with the cutting tool guide surfaces;
manipulating the tibia through a range of motion about the femur
while actuating the cutting tool to cut the femur to form a a
resected surface for the femoral prosthesis; and operably attaching
the femoral prosethesis to the resected surface.
4. The method of claim 3, wherein the wherein the cutting tool
fiber comprises a soft tissue protective sleeve surrounding the
cutting tool proximate a soft tissue region associated with the
medial side of the femur, wherein the soft tissue protective sleeve
is biased to track along a contour of a side of the bone and
prevent the cutting profile from being exposed to the soft tissue
region during the step of manipulating the tibia through a range of
motion about the femur while actuating the cutting tool.
5. An unicondular implantable orthopedic prosthesis for
implantation during a knee arthroplasty procedure, the implantable
prosthesis comprising: an implant body formed of a metallic
material and having a fixation surface facing a bone and an
articulation surface adapted to articulate with respect to another
surface, the fixation surface of the implant body forming a
converging opening such that, when the implant body is viewed in
cross section profile along a mediolateral axis, lines drawn
tangent to an anterior and posterior portions of the upper and a
lower cross section profile will converge at a point anterior of a
posterior surface of the articulation surface.
Description
CLAIM TO PRIORITY
[0001] The present invention claims priority to U.S. Provisional
Application No. 60/551,160, filed Mar. 8, 2004, entitled, "METHODS
AND APPARATUS FOR IMPROVED PROFILE BASED RESECTION," and U.S.
Provisional Application No. 60/551,080, filed Mar. 8, 2004,
entitled, "METHODS AND APPARATUS FOR PIVOTABLE GUIDE SURFACES FOR
ARTHROPLASTY," and U.S. Provisional Application No. 60/551,078,
filed Mar. 8, 2004, entitled, "METHODS AND APPARATUS FOR MINIMALLY
INVASIVE RESECTION," and U.S. Provisional Application No.
60/551,096, filed Mar. 8, 2004, entitled, "METHODS AND APPARATUS
FOR ENHANCED RETENTION OF PROSTHETIC IMPLANTS," and U.S.
Provisional Application No. 60/551,631, filed Mar. 8, 2004,
entitled, "METHODS AND APPARATUS FOR CONFORMABLE PROSTHETIC
IMPLANTS," and U.S. Provisional Application No. 60/551,307, filed
Mar. 8, 2004, entitled, "METHODS AND APPARATUS FOR IMPROVED CUTTING
TOOLS FOR RESECTION," and U.S. Provisional Application No.
60/551,262, filed Mar. 8, 2004, entitled, "METHODS AND APPARATUS
FOR IMPROVED DRILLING AND MILLING TOOLS FOR RESECTION," and U.S.
patent application Ser. No. 11/036,584, filed Jan. 14, 2005,
entitled, "METHODS AND APPARATUS FOR PINPLASTY BONE RESECTION," and
U.S. patent application Ser. No. 11/049,634, filed Feb. 3, 2005,
entitled, "METHODS AND APPARATUS FOR WIREPLASTY BONE RESECTION,"
which claims priority to U.S. Provisional Application No.
60/536,320, filed Jan. 14, 2004, and U.S. patent application Ser.
No. 11/049,634, filed Feb. 3, 2005, entitled, "METHODS AND
APPARATUS FOR WIREPLASTY BONE RESECTION," which claims priority to
U.S. Provisional Application No. 60/540,992, filed Feb. 2, 2004,
entitled, "METHODS AND APPARATUS FOR WIREPLASTY BONE RESECTION,"
the entire disclosures of which are hereby fully incorporated by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention generally relates to methods and apparatus
for bone resection to allow for the interconnection or attachment
of various prosthetic devices with respect to the patient. More
particularly, the present invention relates to methods and
apparatus for improved profile based resection techniques for
arthroplasty.
[0004] 2. Background 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, for example, 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 and other forms of bone
resection for over 30 years. Unfortunately, present approaches to
using existing planar or non-planar saw blade instrumentation
systems all possess certain limitations and liabilities.
[0008] Perhaps the most critical factor in the clinical success of
any bone resection for the purpose of creating an implant surface
on the bone is the accuracy of the implant's placement. This can be
described by the degrees of freedom associated with each implant.
In the case of a total knee arthroplasty (TKA), for example, 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 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 for TKA, the distal resection cutting guide is positioned
by drilling two long drill bits into the anterior cortex across the
longitudinal axis of the bone. 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.
[0009] 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 and other bone resection procedures for
more than 30 years, there are still reports of incidences where
poor cuts result in significant gaps in the fit between the implant
and the bone. Improvements in the alignment and operation of
cutting tools for resecting bone surfaces are desired in order to
increase the consistency and repeatability of bone resection
procedures as is the improvement of prosthetic stability in
attachment to bone.
[0010] One technique that has been developed to address these
challenges has been the profile based resection (PBR) techniques
taught, for example, by U.S. Pat. Nos. 5,514,139, 5,597,397,
5,643,272, and 5,810,827. In a preferred embodiment of the PBR
technique, a side cutting tool such as a milling bit or side drill
bit is used to create the desired resected surface. While the PBR
technique offers many advantages over conventional resection and
arthroplasty techniques, it would be desirable to provide
enhancements to the PBR technique that improve the ability to
address soft tissue management and minimally invasive surgical
techniques.
SUMMARY OF THE INVENTION
[0011] The present invention provides for embodiments of alignment
guides, cutting guides, cutting tools and soft tissue management
techniques for profile based resection (PBR) arthroplasty
facilitating intraoperative and postoperative efficacy and ease of
use. In one embodiment, a manual alignment guide is provided that
permits less invasive incisions by providing soft tissue
accommodating contours or reliefs. In another embodiment, a single
medial drill guide plate is used for the PBR arthroplasty.
[0012] The present invention utilizes a number of embodiments of
cutting tools to remove boney material to create cut surfaces for
prosthetic implant attachment and fixation. The overriding objects
of the embodiments are to provide the ability to perform resection
in very small incisions, the creation of precise and accurate
cut(s), and to provide for soft tissue protection characteristics
and features preventing the tool from accidentally harming soft
tissue. Specifically, many of the cutting tool embodiments
disclosed are either incapable or highly resistant to damaging soft
tissue, or are by means disclosed prevented from coming into
contact with soft tissue in the first place.
[0013] The present invention utilizes a number of embodiments of
cutting guide technologies loosely or directly based on Profile
Based Resection (PBR). The overriding objects of PBR technologies
are to provide for significantly improved reproducibility of
implant fit and alignment in a manner largely independent of the
individual surgeon's manual skills, while providing for outstanding
ease of use, economic, safety, and work flow performance.
[0014] The present invention utilizes a number of embodiments of
alignment or drill guides to precisely and accurately determine the
desired cutting guide location/orientation, thus cut surface
location(s)/orientation(s), thus prosthetic implant location and
orientation. The overriding objects of the embodiments are to
precisely and accurately dictate the aforementioned locations and
orientations while optionally enabling ease of use in conjunction
with manually or Computer Assisted techniques, and while optionally
enabling ease of use in minimally invasive procedures where
surgical exposure and trauma are minimized.
[0015] The present invention utilizes a number of methods and
apparatus embodiments of soft tissue management techniques and the
devices supporting said techniques. The overriding object of these
embodiments is to take advantage of the anatomy, physiology, and
kinematics of the human body in facilitating clinical efficacy of
orthopedic procedures.
[0016] 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." The present invention
provides a method and apparatus for reducing implant placement
errors in order to create more reproducible, consistently excellent
clinical results in a manner that decreases risk to soft tissue,
incision or exposure size requirements, manual skill requirements,
and/or visualization of cutting action.
[0017] It should be clear that applications of the present
invention is not limited to Total Knee Arthroplasty or the other
specific applications cited herein, but are rather universally
applicable to any form of surgical intervention where the resection
of bone is required. These possible applications include, but are
not limited to Unicondylar Knee Replacement, Hip Arthroplasty,
Ankle Arthroplasty, Spinal Fusion, Osteotomy Procedures (such as
High Tibial Osteotomy), ACL or PCL reconstruction, and many others.
In essence, any application where an expense, accuracy, precision,
soft tissue protection or preservation, minimal incision size or
exposure are required or desired for a bone resection and/or
prosthetic implantation is a potential application for this
technology. In addition, many of the embodiments shown have unique
applicability to minimally invasive surgical (MIS) procedures
and/or for use in conjunction with Surgical Navigation, Inage
Guided Surgery, or Computer Aided Surgery systems.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] 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:
[0019] FIGS. 1, 2, and 3 are pictorial representations standard
incision sizes or exposure required by the prior art, while FIG. 4
is a pictorial representation or approximation of one form of
surgical exposure that is desired.
[0020] FIGS. 5-130 show various depictions of embodiments and
methods in accordance with alternate embodiments of the present
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] It should be noted that, in many of the figures, the cut
surface created by the cutting tool in accordance with the
techniques of the present invention are shown as having already
been completed for the sake of clarity. Similarly, the bones may be
shown as being transparent or translucent for the sake of clarity.
The guides/pins, cutting tool, bones, and other items disclosed are
may be similarly represented for the sake of clarity or brevity
FIGS. 1 Through 4
[0022] FIGS. 1 and 2 show conventional surgical exposures and
instrumentation being utilized. FIG. 4 shows a reduced incision
currently utilized in performing the current state of the art in
`minimally invasive` Unicondylar Knee Replacement.
FIGS. 5 Through 11
[0023] FIGS. 5 through 11 concentrate on alignment guide and/or
drill guide techniques. FIG. 5 shows a manually operated alignment
guide suitable for use with surgical exposures similar to that
shown in FIG. 2 (it should be noted that surgical navigation
sensors could be used to assist in determining final drill guide
location and orientation). FIGS. 6 and 7 show an improvement upon
the embodiment shown in FIG. 5 for enabling manual alignment guide
use in less invasive incisions by providing soft tissue
accommodating contours or reliefs. In other words, for a medial
parapatellar incision, the alignment guide is configured to allow
for appropriate contact and referencing of the distal and posterior
femoral condyles, the IM canal (when not relying on an
extramedullary reference or inference of the mechanical axis) or IM
Rod, the anterior cortex or anterior runout point of a given or
proposed implant size (via a stylus not shown), and the epicondylar
axis via palpitation or visual reference while the patellar tendon,
patella, and/or quadriceps tendon is draped over the lateral side
(right side as shown in the figures) of the alignment guide
allowing insertion of the guide when the patella is neither everted
not fully dislocated as in conventional techniques.
[0024] It should be noted that initial alignment indicated by
reference of the distal femur can be further adjusted in all six
degrees of freedom as a fine tuning for final cut location and
orientation. This simply calls for the inclusion of additional
adjustment of the location and orientation of the crossbar
mechanism and/or rotational alignment arm, with respect to the
initial reference provide for by contact between the body of the
guide and the bone (optionally including the IM Rod), in
flexion-extension angulation, varus-valgus angulation (rotational
angulation and Anterior-Posterior location are already shown),
mediolateral location (represented in this embodiment of the
current invention by the cross bar mechanism in FIG. 5 where drill
guide mediolateral location is shown as being independently and
infinitely adjustable), and proximal-distal location (as shown in
FIGS. 5, 6, and 7--it should be noted that this adjustment might be
best embodied in an infinitely adjustable slide as opposed to the
incrementally adjustable slide shown, and that simple marking would
be present indicating the relative movement of the slide with
respect to the body). It may be desirable to only utilize only a
medial drill guide plate with multiple drill guide bushings to
create holes extending partially or completely across the femur
depending upon the manner in which the guides are to be connected
to the femur.
[0025] FIGS. 8, 9, and 10 show an alternative alignment/drill guide
embodiment of the present invention wherein a cannulated surgically
navigated handle/drill guide is used to create fixation apertures
in the bone for direct or indirect fixation of a cutting guide. As
shown in FIG. 8, it may be advantageous to include tines for
penetrating the bone to obtain initial stabilization of the handle
in the location and orientation indicated by the surgical
navigation system ("Surg Nav"--this term shall be used
interchangeably with Computer Aided Surgical System or Image Guided
Surgical System throughout this disclosure) prior to extending the
drill, represented in FIG. 10, into the bone to create the
aperture. It should be noted that the aperture, or hole, thus
created could be blind or extended to a specific depth, or
optionally extended entirely through the bone and out the furthest
side of the bone. Importantly, this process could be utilized
transcutaneously through a small stab wound (perhaps 4 mm in
length) through the skin to the bone surface, or through a
preformed incision through which other instrumentation of the
present invention or other devices may be introduced during a
procedure. Further, although only one cannulation is shown, a
single handle may desirably contain multiple cannulations, some or
all of which could be adjustably extended into contact with the
bone to reduce any wandering of the drill contacting oblique bone
surfaces and improve the precision and accuracy of aperture
creation (thus allowing for the creation of apertures in the medial
side of the femur, represented in FIG. 11, with a single Surg Nav
Handle. Also, the apertures may be configured such that the femoral
and tibial apertures shown in FIG. 11 are all created using a
single positioning step for the handle). As represented in FIG. 9,
there is very little distance over which the drill is cantilevered
between its guidance within the cannulations and its point of
initial contact with the outer surface of the bone. This aspect of
this embodiment of the current invention is critical in preserving
the potential accuracy of Surg Nav systems, i.e.; the navigation
system (the computer and the sensors) may be capable of determining
appropriate location and orientation to .+-.0.1 mm and .+-.0.5
degrees, but if the location and/orientation of the aperture
created represents some path of least resistance in bone which is
followed by the drill, the resultant location and orientation of
cut surfaces, and thereby the location and orientation of the
prosthesis attached thereto, will likely be seriously in error.
[0026] It should also be noted that the methods described herein
are applicable to the methods demonstrated in Provisional Patent
Application Ser. No. 60/536,320, entitled "Methods and Apparatus
for Pinplasty Bone Resection" and Ser. No. 60/540,992, entitled
"Methods and Apparatus for Wireplasty Bone Resection," the
disclosures of each of which are hereby incorporated by
reference.
FIGS. 12 Through 34
[0027] FIGS. 12-34 disclose embodiments of the present invention
for creating planar and/or curvilinear resection surfaces on or in
the proximal tibial and other bones and embodiments of the present
invention for prosthetic implants.
[0028] FIGS. 12-15 represents an embodiment of the present
invention for cutting guides and cutting tools which substantially
comprises a guide with guide pivot aperture(s) and a guide pivot
reference surface(s) for mating with a bushing controlling a
cutting tool, wherein the bushing possess a bushing reference plane
(which mates with the pivot reference surface(s) of the guide), a
bushing pivot pin, best represented in FIG. 88 (which mates with
the guide pivot aperture(s) of the guide), and a cannulation for
articulated and/or axial guidance of the cutting tool.
[0029] There are a number of optional features that are highly
desirable depending on the preferred method of use utilized for
these embodiments of the present invention. The soft tissue
protection tip of the cutting tool and the integral soft tissue
retractor feature of the bushing body are two principal examples
represented in FIG. 20. The soft tissue protection tip can be
integrally formed as a part of the cutting tool during its
manufacture, be a separate component attached to it, and may, in
one preferred embodiment, be free to rotate with respect to the
cutting tool (which would be useful in preventing rotating bearing
contact between the tip and soft tissue). The integral soft tissue
protector in beneficial in preventing or mitigating contact between
soft tissue near the area where the cutting tool enters, cuts, and
exits the wound (in other words, to the right and left of the
bushing body shown in FIG. 13). If the incision is pictured as
being a window into the joint which is somewhat elastically
moveable from side to side, the integral soft tissue retractor
would act to shift that window to mitigate or prevent contact
between the soft tissue (specifically the patella tendon, medial or
lateral collateral ligaments, the capsule, skin, fat, etc.) and the
cutting surfaces of the cutting tool.
[0030] In operation, the guide is properly positioned with respect
to the proximal tibia and the cut to be created thereon and
robustly fixed with respect to the tibia or directly to the tibia.
This can be accomplished by manual alignment means outlined in U.S.
Pat. No. 5,643,272 for manually positioning guides then fixing them
in place, or use the '272 apparatus and methods to create the
fixation apertures shown in FIG. 11 or 12, or use the Surg Nav
techniques described herein as shown or in conjunction with the
methods described in the '272 patent. The bushing body is then
engaged with the guide. Three primary methods of initiating cutting
of the proximal tibia are preferred. The first, or `Tangent
Method`, is initiated by extending the side cutting drill through
the bushing body cannulation and into contact with a side of the
tibia and then sliding the optional non cutting tip along the face
of the bone until the cutting surfaces of the cutting tool were
first in contact with the side of the bone. At this point, the
cutter could be actuated to begin cutting the boney tissue to
create the cut surface. As the non-cutting tip cannot cut bone, its
edges would remain at all times immediately beyond and adjacent to
the boundary of the cut surface being created. The diameter or size
may be greater or less than the diameter or size of cutting
surfaces of the cutting tool. Note that although the embodiment of
the cutting tool shown is a side cutting drill, a modified rat tail
rasp driven by a reciprocating driver could also work well--any
cutting tool capable of cutting in a direction orthogonal to its
long axis is considered to be within the scope of the present
invention. As best represented in FIG. 15, the entirety of the
resected surface may be prepared in this manner.
[0031] The second primary method is the `Plunge Then Sweep` method.
In this method, the cutting tool or optionally a pilot drill would
be plunged completely or partially across the surface to be cut.
Then the cutting tool could be swept back and forth in clockwise
and counter-clockwise directions while being axially manipulated to
complete the cuts.
[0032] The third primary method is the `Chop Then Sweep` method
represented in comparing FIGS. 88 and 89. In this method, the
cutting surfaces of the cutting tool are positioned over and at
least partially across the uncut bone, then chopped down into it by
manipulating the bushing. In other words, the bushing pivot pin is
engaged with the pivot aperture with the cutting tool positioned
over the bone which positions the bushing reference surface at a
distance above the pivot reference surface, then the bushing is
moved downward along the axis of the bushing pivot pin while the
cutting tool is under power until the cutting tool reaches the cut
surface to be created (if the cutting tool is a side cutting drill,
the cutting surfaces would be tangent to the desired cut surface at
that time). The bushing is then manipulated as described
hereinabove to complete the cuts. Importantly, the pivot reference
surface and pivot aperture could be slidably mounted to a base
component fixed with respect to the tibia so that the surgeon may
manipulate the bushing body to simultaneously create the cut and
move the pivot aperture with respect to the tibia. This embodiment
will enable the surgeon to easily compensate for any soft tissue
condition encountered clinically while preserving the benefits of
the present invention. Methods combining the aforementioned primary
methods are considered to be within the scope the present
invention. Importantly, most standard or prior art tibial resection
cutting guides may be simply modified to include the pivot
apertures described herein.
[0033] FIGS. 16 through 21 describe another embodiment of the
present invention. As shown in FIG. 16, this embodiment includes a
Base and a Rotational/Translational Pivot Arm coacting to allow for
infinite manipulation of the bushing pivot pin location within a
desired plane during the process of removing material from the
proximal tibia or other bone. Movement of the
Rotational/Translational Pivot Arm in both rotational and
translational degrees of freedom within a desired plane allows for
any combination of rotational and translational movement of the
axis of the bushing pivot pin within its desired plane. In other
words, this embodiment of the present invention allows for infinite
and continuous adjustability of cutting tool location and
orientation with respect to the bone or bones being cut while
providing for accurate and precise cut surface creation.
[0034] FIGS. 22 through 28 represent another embodiment of the
present invention whose principal of operation are similar to
previous embodiments, with the exception of including a depth
limiting contour which acts as either a definitive limitation for
cutting tool depth or as a general guideline for a surgeon to
follow as the patient's clinical presentation and the surgeon's
judgment dictate. Although the embodiment shown is directed toward
Unicondylar tibial preparation, it should be noted the any clinical
application where such definitive or guideline type depth guidance
is desirable.
[0035] FIGS. 29 and 30 show an embodiment of the present invention
directed toward endplate preparation in spinal reconstruction where
the endplates are prepared to receive a prosthetic implant. It is
interesting to note that the profile of the cutting path of the
guide represented in FIG. 30, in this embodiment, is geometrically
identical to the cutting path of the resected surface created by
the passage of the cutting tool shown. This could be very helpful
in clinical application where such a device where inserted into a
wound such that, while the surgeon could not visually observe the
cutting tool while it removes boney material, he could, by way of
the guide geometry, observe where the cutting is with respect to
the bone being cut by looking at the position (represented by "POS
1" and "POS 2") of `Pivot 2`, represented in FIG. 30, with respect
to its location in contact with the guide as it traverses the
cutting path of the cutting guide. This embodiment is also highly
applicable to tibial resection and could allow for cut geometries
that are anatomically curved in both AP and ML profiles to both
preserve bone and improve fixation quality and load transfer
characteristics between the implant and the bone by converting the
shear component load of conventional planar tibial components into
compressive loads via geometrically normal or transverse abutment
of bone and implant surfaces in the direction of A-P and/or M-L
and/or torsional shear loading. An implant design embodying
fixation geometries for mating with such cut surfaces is highly
desirable. In one embodiment of such a tibial prosthesis design,
the fixation surfaces would be intended to mate, directly or
indirectly, with cut surfaces represented in FIGS. 33 and/or 34
(the tibia in the right side of the FIG. 34). In essence, the
tibial implant would possess a planar or gently curvilinear `rim`
for contacting the `cortical skim cut` surface (represented in FIG.
32), and convex fixation surfaces for direct or indirect fixation
to the concave tibial cuts represented in FIGS. 33 and 34. Direct
fixation to such surfaces could be achieved by high precision
resection of both the cortical rim, for attachment of the rim of
the tibial prosthesis, and the concave surface(s), for intimate
apposition to the convex implant surfaces. Such fixation,
specifically of the concave bone cuts to the convex implant
surfaces, could be achieved by way of an interference fit between
the cuts and the implant along one axis (for instance, a front to
back--AP--axis or direction), or along two axes (for instance, AP
and Side to Side--ML--axes), or circumferentially (in other words a
bit like a pin of a given diameter being forced into a hole of a
lesser diameter), or both circumferentially and along an axis at
roughly a 90 degree angle or normal to the skim cut surface when
viewed in one or two orthogonal planes (an "up and down axis" or
superior-inferior or proximal distal direction). It should be noted
that an interference fit in a roughly superior-inferior direction
may call for a textured surface on the bottom most surface of the
convex fixation surfaces presents a small surface area of contact
at initial contact with the bottom of the concave cut to allow the
implant to compact a reduced area of cancellous bone as the implant
is impacted in a superior to inferior direction until it reaches
its desired superior-inferior location and/or contact between the
rim of the implant and the skim cut of the cortices. As compared to
previous methods of achieving implant fixation, these embodiments
of the present invention yield superior stability of implant
fixation to bone to an extent reminiscent of the difference between
riding a horse wearing a deeply dished saddle and riding a very
sweaty horse bareback.
[0036] An alternative fixation paradigm allows for less intensive
demands for the precision of the fit between concave tibial cuts
and convex fixation surface. In essence, the concave surface may be
`excavated` in any desired manner (such as the Cutting Trials shown
in FIG. 31 which cut the proximal tibia while the tibia is moved
through at least a portion of its range of motion about the femur),
and a morselized or granular osteobiological substance, perhaps
tricalcium phosphate, HATCP, or other substances generally
described as `bone substitutes` or autograft or allograft
cancellous or cortical bone (it would be very useful to use the
bone which was removed from the tibia or other patient bone during
the creation of the cut(s) in that it is readily available and
completely avoids the issues of disease transmission or immune
response), is then impacted into the concave surface using a `form`
to create a surface of impact material (referred to herein as the
"Impacted Surface") of specific shape and location/orientation with
respect to the cortical skim cut and/or the tibia or femur. This
form is beneficially shaped in a manner related to the shape of the
convex implant fixation surface shape so as to create a specific
geometric relationship between the implant fixation surfaces and
the Impacted Surface geometry. In one embodiment of the present
invention, the fit between the implant and the Impacted Surface
would be an interference fit or press fit. As properly impacted
morselized cancellous bone is known to achieve stiffnesses (or
modulus of elasticity) which approach as much as 80% of the
stiffness of cortical bone in compression, robust intraoperative
fixation may be achieved in this manner.
[0037] In another embodiment, the fit would leave a significant
gap, perhaps 0.2 mm to 4.0 mm in width, between portions or all of
the convex fixation surfaces of the implant and the convex cut(s),
into which bone cement or other substance would then be injected or
impacted achieving interdigitation with both the surfaces of the
prosthesis and the material of the Impacted Surface. This results
in what could be described as composite interface of both
biologically active and non-living but structurally robust
materials to facilitate both immediate intraoperative stability by
way of simple mechanics and long term stability by way of improved
load transfer between the implant and the bone eliciting a
beneficial biological response by the bone to said loading
resulting in intimate and mechanically robust apposition between
the composite interface and living tissue. It should be noted that
such a method prevents excessive micromotion or strain at the
interface between the implant (and/or the composite interface) and
living tissue during the postoperative healing process, which, in
essence, gives the bone a chance to further stabilize its fixation
to the implant by way of bone modeling or remodeling in response to
load transfer. Specifically, it is highly beneficial to maintain
the strain state within living bone at and/or in the general
vicinity of the bone implant interface within a range of 50
microstrain to 4000 microstrain so as to elicit the formation of
bone tissue at and around the interface--strain levels in excess of
4000 microstrain or less than 50 microstrain are very likely to
elicit the formation of fibrocartilagenous tissues at the interface
which may lead to aseptic loosening of the implant.
[0038] In the embodiment where the bone cement is injected, a small
hole located at or beneath the skim cut allows for the injection of
the material beneath the implant to achieve intimate and controlled
interdigitation. Alternatively, the implant could be seated `over`
the freshly cut concave surfaces, and a slurry of biologically
active and/or mechanically robust material(s) injected into the
gaps between the implant and the bone under controlled pressure.
Injection could be achieved via the portal shown in FIG. 34. Such a
slurry may comprise a mixture of substances such as morselized
patient bone and bone cement, but alternative or additional
materials including bone substitutes, osteobiologicals such as bone
morphogenic proteins, antibiotics, or even living cells such as T
cells known to promote post-operative healing and long term implant
fixation. Beneficially, a fin feature may be added to these
embodiments to facilitate additional mechanical stability, and said
stem feature could beneficially possess an aperture for cross-pin
fixation as described below for use in conjunction with the cross
pins represented in FIG. 111.
[0039] Importantly, it is an objective of the embodiments of the
present invention to preserve living, structurally viable bone
tissue to facilitate the efficacy of any subsequent revision
procedures. Further, the location and geometry of the concave
tibial cut allows for the use of a bearing insert (conventionally
made of materials such as polyethylene or other materials capable
of `whetting` or mimicking the benefits of `whetting` during
bearing contact; mimicking constituting, in one embodiment, the
absence or mitigation of wear debris generation despite the
application of significant bearing forces, in TKA in excess of 200
lbs and often as much as 500 lbs or more) whose `underside` is
convexly shaped to mate with a concavely shaped mating or
accommodating surface in the upper surface of the tibial implant or
`baseplate` as it is sometimes referred to. This allows for a
tibial insert(s) whose thickness, in the areas beneath where the
femoral implant bears against the tibial insert, may be equal to or
greater than those insert thicknesses used in the past (those
associated with predominantly planar tibial cuts) while require
removal of significantly less structurally viable bone from the
cortical rim of the proximal tibia than past efforts. Determination
of the geometry and location of the baseplate's concave surface and
therefore the areas of greatest insert or bearing surface are
easily determined by analysis of the wear patterns of retrieved
tibial inserts. These embodiments of the present inventions also
facilitate significant clinical benefits when applied to meniscal
or rotating platform TKA designs as a high degree of conformity may
be achieved while constraint is mitigated while preserving
significantly more bone than prior art devices. Further, the
reproducibility of the methods and apparatus described herein
enable independent attachment of single compartment implants to
bone to achieve Unicondylar, Bicondylar, Bicondylar and
Patellofemoral, or Unicompartmental and Patellofemoral replacement
of damaged bone surfaces while achieving the objectives of bone
preservation, robust immediate and short and long term fixation,
reproducibility of implant fixation and resulting location and
orientation, and intraoperative ease of use.
[0040] It should be noted that the cutting profile of the cutting
tool shown in FIG. 29 is curved in manner beneficial to endplate
preparation in intervertebral fusion, dynamic disc replacement,
and/or nucleus replacement as the cutting profile closely
approximately the natural geometry of the endplates and provides
for intimate fit with such prostheses fixation surfaces. In
adapting this embodiment to tibial resection in either partial or
complete knee replacement, the cutting profile of the tool would be
shaped as desired to create the aforementioned cut surfaces in
either one continuous movement of a single cutting tool, or
incremental use of one or more cutting tools to cut bone to the
desired shape and in the appropriate location and orientation, in
all degrees of freedom, with respect to the tibia and/or femur
and/or patella and/or soft tissues of the knee joint.
[0041] In many applications of the tibial resection embodiments and
methods described herein it is desirable that the Superior-Inferior
thickness or diameter of the cutting tools used be less than the
thickness of the bone to be removed in the creation of the cut
surfaces so that the cutting surfaces of the cutting tool not
contact soft tissue surface and bone surfaces located above the
bone being removed. Alternatively, the cutting tool could be of
such a thickness or diameter as to allow for the resection of both
the femur and the tibia, or any such contiguous bones, to be
prepared simultaneously with the passage of the cutting surfaces of
a single tool across or along cut surfaces being created on both
bones. Maintaining the desired geometric relationships between the
contiguous or adjacent bone ends would be key in this embodiment of
the present invention and could easily be obtained and maintained
by use of a bracket fixed to the bones to establish and maintain
the geometric relationship between said bones (see FIG. 30 for one
embodiment of such a bracket employed to establish and maintain
alignment between adjacent vertebral bodies.
FIGS. 35 Through 98
[0042] FIGS. 35 through 98 show embodiments of the present
invention for femoral resection. For the sake of clarity, it should
be noted that any combination of the forms of the present invention
disclosed herein may be modified or combined to form constructs not
specifically disclosed herein, but still within the scope of the
present invention. The embodiments represented in FIGS. 29 and 30
are outstanding examples of this, as one of ordinary skill in the
art would clearly recognize the applicability and benefits of this
embodiment for tibial and/or femoral resection in Unicondylar or
Bicondylar procedures, for bone resection in ankle replacement or
arthrodesis (fusion), mandibular advancement procedures, high
tibial osteotomy procedures, proximal femoral and acetabular
preparation in Hip Arthroplasty, and a list of other applications
too long to list in detail where reproducible and safe removal of
living tissue during surgical intervention is beneficial.
[0043] FIGS. 35-40 show embodiments of the present invention for
use in a manner similar to that described in previously-referenced
co-pending provisional application, entitled "METHOD AND APPARATUS
FOR WIREPLASTY BONE RESECTION."
[0044] FIGS. 35-40 shows an embodiment of the present invention
wherein the guide plates and guide surfaces are located entirely
outside the wound, but the side cutting drill and handle construct
are not passed through mediolateral soft tissue portals described
hereinabove. The side cutting drill controlling portion of the
handle is essentially 'snaked` into the less invasive
wound/exposure/ approach/incision and the guide engagement features
are engaged to the cutting guide at a location entirely outside the
wound. As long as the axis of the engagement feature is maintained
as coaxial with the side cutting drill, the desired cut geometries
will be attained despite manipulation of the handle with respect to
the guide. This method can be utilized to complete some or all of
the desired cuts. Also, this embodiment of the current invention
can be used to perform the posterior cut, posterior chamfer cut,
and distal cut optionally using kinematic resection to reduce
exposure requirements, and then removed from the wound and guide,
flipped over 180 degrees from the orientation shown in FIG. 39,
reinserted into the wound and into engagement with the guide to cut
the anterior chamfer cut and anterior cut with or without
implementation of a kinematic resection technique and, optionally,
with the knee in 15 degrees to 45 degrees to facilitate the soft
tissue laxity and ease of use previously described. It should be
noted that the mechanism for driving the side cutting drill is not
represented in these figures and that a number of different options
may be used.
[0045] One way to accomplish drive input is generically represented
in FIG. 40, where a flexible drive shaft or bevel gear arrangement
may be utilized to drive the side cutting form drill shown.
Alternatively, chain, belt, or pneumatic drive mechanisms may also
be used. FIG. 40 also represents an embodiment of the present
invention which allows for the accurate and precise preparation of
curvilinear cut surfaces, beneficially used in conjunction with
guides containing curvilinear guide surfaces as represented in
FIGS. 61 and 62, to create cut surfaces for intimate attachment and
fixation to implants represented in FIGS. 125, 126, and/or 127.
FIG. 116, 117, and 118 show representations of the cutting paths of
cuts for seating conventional total condylar implants compared with
the cutting paths of this embodiment of the present invention.
These figures also demonstrate the dramatic degree to which viable
bone preservation may be achieved while simultaneously providing
for superior fixation and Range of Motion with articular
conformity. This improvement in articular surface conformity in the
deepest ranges of motion of the knee joint is especially critical
for physically active patients and in cultures where deep knee
flexion is needed to squat or kneel. As is noted in the figure,
conformity between the tibiofemoral articular surfaces of the
femoral component and the tibial bearing surface may therefore be
maintained in deepest flexion to as much as 140 degrees of flexion
to 170 degrees of flexion depending on the activities of the
patient. Prior Art implants, such as the one shown in the
radiograph ("xray") FIG. 113, do not offer such benefits.
[0046] FIGS. 41 through 60 represent an embodiment of the present
invention for Triple TKA, similar to that described in the
previously-referenced application entitled, "METHOD AND APPARATUS
FOR WIREPLASTY BONE RESECTION". As noted in that provisional
application, an additional feature that may be desirable to add to
different embodiments of the present invention are the soft tissue
protection sleeves shown in FIGS. 42 and 43. One clinical
application calling for the benefits of this feature would be
Transcutaneous Transarticular TKA ("TTTKA" or "Triple TKA" or "T
Cubed" or "T.sup.3" Procedures) where a PBR cutting guide, as
generally shown in FIG. 35 is positioned completely outside of the
wound with the exception of fixation features which extend from the
externally located guides through skin incisions and into holes or
apertures created in bone. As shown in FIGS. 52 and 53, the cutting
tool, in the case of the present invention a side cutting drill, is
extended through the handle, the guide, the skin, fat, capsule, etc
(soft tissue), across, across and in front of, through, or beneath
the articular surfaces of the joint, and through the soft tissue,
guide, and handle on the opposing side of the bone. The soft tissue
protection sleeves may be extended through the soft tissue and into
contact with the sides of the bone. The retaining lip can be used
to maintain the sleeves in contact with the bone and are held there
by the edges of the incision through the capsule during cutting.
The springs shown in FIG. 43 can further bias the sleeves into
contact with bone in a manner that would maintain that contact as
the width of the bone changed along the cutting path of the
resected surface.
[0047] One skilled in the art will note that the thicknesses for
the soft tissue through which the sleeves extend change
significantly from patient to patient thus requiring the
proportions of the sleeve, spring and other components of the
present embodiment of the invention to change accordingly. For
example, in an obese patient, the fat layer through which the
cutting tool extends can be 5 inches thick per side or more. The
diameter of the soft tissue protection sleeve can be significantly
reduced with respect to what is shown as the side cutting drill
diameter is reduced, thus requiring a smaller capsular or other
soft tissue incision or `stab wound`.
[0048] In operation, the handle is manipulated to traverse the
cutting path of the cutting guide while the tibia is swung through
a range of motion about the femur as shown in comparing FIGS. 54
through 60. This particular principal of operation takes advantage
of the fact that the capsule, the patella, and to a lesser or
greater extent the skin, moves with the tibia as it moves through a
range of motion with respect to the femur. Thus, a small, perhaps 4
mm to 10 mm long stab wound through skin to the medial side of the
posterior femoral condyles (roughly in line with the axis of the
pilot drill shown in FIG. 51) with the knee bent in flexion, and
then looked at the side of the femur (through the portal created by
the stab wound) while moving the tibia through a range of motion,
the side of the femur would be observed to be passing by/through
the portal. In order to complete all of the resected surfaces on
the femur necessary to fix a standard femoral prosthesis, it may be
necessary in one embodiment to make two passes with the side
cutting drill sweeping about the femur with the tibia as
represented in FIGS. 54 through 60.
[0049] FIGS. 44 through 51 represent an embodiment of the present
invention for use in creating pilot holes allowing for introduction
of a side cutting drill or other cutting tool in Triple TKA or
Unicondylar or Bicondylar procedures. Of particular interest, the
pilot drill is designed to eliminate or mitigate any deviations of
the drill from its intended location and orientation as it is
guided to create portals in living bone. Standard drills tend to
follow the path of least resistance into and through bone often
resulting in either poor drill placement, and thereby poor cutting
guide placement, or improperly located and oriented portals or
apertures for fixation of a cutting guide resulting in poor cutting
guide placement. As shown in FIG. 44, the pilot drill possesses
cutting teeth that are very aggressive in side cutting. This is
critical in that it prevents deflection of the cutting tool when it
contacts tissue of varying material properties. This area of very
aggressive side cutting teeth is relatively short, and is followed
by a longer smooth portion of the shaft of the drill which is
designed to be incapable of cutting bone, but may beneficially
include smooth flutes allowing for removal of chips during the
cutting process. A pilot drill of this kind, optionally used in
conjunction with the Surg Nav Drill Guide of FIGS. 8 through 11,
would be outstanding for use in creating the apertures in bone
desired for positioning the cutting guides. Specifically, the pilot
drill may provide sufficient accuracy and precision of aperture
creation to allow for drilling all the way through or across a bone
to which a cutting guide will be attached to bone sides of the
aperture as shown in FIG. 68, where the cancellous bone within the
cortical shell is not shown for the sake of clarity.
[0050] In use with the embodiment of the present invention, with
the soft tissue protection sleeves of the milling handle in contact
with a bone surface, the pilot drill would be plunged through the
bushings of the milling handle and across the joint, as shown in
FIGS. 45 through 51. FIG. 51 represents the pilot drill having been
plunged entirely across the joint, but with the milling handle not
shown for the sake of clarity. Thus, a portal has been created
across the entirety of the joint for subsequent insertion of the
side cutting drill shown in FIGS. 52 and 53, or any other cutting
tool. It should be noted that in embodiments adapted for use in
Unicondylar knee replacement, it would only be necessary to create
the portal in one side of the joint for extension of the cutting
tool across only a single condyle (as is seen in comparing FIGS. 78
and 80). An alternative embodiment and method of the milling handle
of the present invention represented in FIG. 54 would be to extend
the side cutting drill, or other cutting tool, through a soft
tissue portal on one side of the joint, across the entirety of the
bone surfaces to be resected or cut, but not extend the tool
through the soft tissue on the far side of the joint. As control of
the side cutting drill by the milling handle is very robust, even
when it supports only one spindle of the side cutting drill,
accurate and precise preparation of the distal femur can be
performed without necessitating a second soft tissue portal, and
the soft tissue trauma associated with it, no matter how minor, on
the far side of the joint.
[0051] Alternatively, a hybrid embodiment of externally and
internally located guide surfaces would allow for high precision,
high accuracy cutting without necessitating the creation of soft
tissue portals for insertion of the cutting tool. This embodiment
of the present invention may be attained by positioning one PBR
cutting guide surface(s) in the wound (perhaps looking like the
medial guide surface of the cutting guide shown in FIGS. 68 through
70) and interconnecting it with an externally located PBR cutting
guide surface(s) (perhaps looking like the laterally located plate
in FIG. 60). This would allow for single spindle guidance of the
side cutting drill or other cutting tool in a very robust manner,
while minimizing the trauma to soft tissues necessary to implement
these embodiments. Furthermore, the use of these single spindle
embodiments lend themselves to easy manipulation of the cutting
tool in pivotally sweeping (see FIG. 85) a cut surface while
manipulating the cutting tool axially with respect to the milling
handle. Thus the anterior chamfer cut, distal cut, and posterior
cut could be completed by sweeping the cutting tool along the
cutting path of the cut surface, and the anterior and/or posterior
cuts could be completed by pivotally sweeping the cutting tool as
mentioned above while maintaining the stability inherent in guiding
the milling handle on guide surfaces on opposing sides of the cut
being created. This is beneficial in that the internally located
guide surfaces could be truncated or shortened significantly
allowing for both easier insertion into the surgical exposure and
reduction in the exposure necessary to accommodate the embodiments
in clinical use.
[0052] FIGS. 61 through 62, represent embodiments of the present
invention for use in bone preserving resection techniques. As noted
in FIGS. 61, 116, 117, and 118, a significant amount of viable bone
tissue may be preserved while maintaining all functional paradigms
of conventional TKA while improving articular conformity in the
deepest ranges of flexion. It is of particular interest to note
that this is especially applicable in improving the results of
conventional Unicondylar implant performance, as the current state
of the art makes minimal planar posterior cuts which prohibit
articular conformity in deep flexion. This is something of a `catch
22` as Unicondylar replacement is most often implemented in younger
patients whom place higher functional demands, specifically they
bend their knees more deeply than their older counterparts, on
their implants, yet in an effort to preserve bone for revision,
most uni's don't possess nearly the range of motion with conformity
necessary. Thus a Unicondylar design incorporating deep flexion
articular surfaces (as shown in FIG. 116) and corresponding
fixation surfaces could simultaneously offer articular conformity
and bone preservation for these younger or more physically active
patients who are more likely to demand higher performance and
require revision to TKA.
[0053] FIGS. 63 through 66 represent an embodiment of the present
invention which would facilitate PBR cutting of, in one embodiment,
the posterior chamfer cut, distal cut, and anterior chamfer cut,
and any combination of plunging, pivotally sweeping, and walking
manipulations represented in FIGS. 64 through 66 to complete the
remaining cuts.
[0054] FIGS. 67 through 71 represent ultralow profile PBR
embodiments of the present invention, which, as may be seen in
comparing FIGS. 69 and 71, lend themselves to minimally invasive
implementation while preserving the outstanding clinical
performance characteristics of PBR. The embodiment of the milling
handle shown utilizes milling handle retaining features of the
copending provisional applications referenced herein. As is seen in
comparing FIGS. 67 and 68, the cutting guides shown are fixed to
bone surfaces located to the sides of bone surfaces to be cut for
fixation to the implant. Some surgeons may not want to create such
apertures in living tissue that will then have to heal
postoperatively. This may be avoided easily by modification of the
guide represented in FIG. 68. Instead of creating the apertures in
bone to the sides of the cuts, the apertures are formed in bone
that will be removed upon completion of the anterior chamfer cut
and the posterior chamfer cut. The cutting profile of the cutting
guide shown in FIG. 68 would thereby be modified to allow the
cutting profile of the cutting tool to traverse a cutting path
that, in one embodiment, would complete the anterior cut, a portion
of the anterior chamfer cut, the distal cut, and the posterior cut.
Completion of any remaining cuts could then be completed in any
manner known in the art, such as using the partially cut surfaces
as a guide for their completion, attachment of a cutting guide to
cut surfaces (such as a conventional chamfer cutting block), or a
profiled chisel with cutting surfaces or edge which possessed the
exact profile, or resected surface "cutting path", of the cuts to
be created and would be plunged across the surfaces being cut in a
side to side or mediolateral direction. It should be noted that the
profiled chisel embodiment of the present invention would be
particularly useful when used in conjunction with the side to side
oriented embodiments of Pinplasty style cutting systems, or
alternatively, for use with single plate versions of the PBR guides
represented herein and/or in the copending applications referenced
herein.
[0055] FIGS. 72 through 82 represent embodiments of the present
invention for use in Triple TKA or modified Triple Knee
Arthroplasty as noted in the copending applications. It is of
particular interest to note that the side cutting drill shown in
FIG. 80 could be modified to possess and non-linear or curvilinear
or curved cutting profile such that it would more closely resemble
the side cutting drill shown in FIG. 27 of U.S. Pat. No. 5,810,827.
FIG. 76 shows a combination pilot drill and side cutting drill
embodiment of the present invention. It is of particular interest
to note that although single radius cut per aperture in bone is
represented, that multiple radii or even planar cuts are easily
generated by modifying the embodiment of the handle shown in FIG.
74 to include a cam or radial displacement mechanism which would
continuously or incrementally change the distance from the
centerline of the cutter and the centerline of the aperture in
response to the angular location of the handle with respect to the
bone, as represented in FIG. 79. In other words, the radius changes
as a function of angle theta to create the desired cut geometry for
fixation of the implant. Any mechanisms enabling precise,
controllable axial displacement in response to angular displacement
is consider to be within the scope of this embodiment of the
present invention.
[0056] FIGS. 83 through 92 represent apparatus and methods for use
in preparing planar or curvilinear cuts. The embodiments of the
sweeping guides (perhaps more precisely described as being
"pivotally sweeping guides") shown in FIGS. 83 through 87 were
previously described in copending applications referenced herein.
Stability of fixation of the cutting guides to the bone is critical
in this embodiment as the forces imparted to the bushing must be
resisted by the guides lest the resulting cuts vary from their
intended location and orientation. One outstanding solution to this
issue would be the implementation of a Cam Pin fixation embodiment
of the present invention in place of at least one of the fixation
nubs shown in FIG. 83. The intent of this cam pin invention is to
`preload` the fixation of the cutting guide to the bone in a manner
that allowed the combination of the bone and cutting guide to act
as one continuous structure in resisting deflection of the bushing
during bone cutting. This desired end result is attained by having
at least one of the fixation nubs being rotatably engaged to the
cutting guide such that the axis of the cylindrical surface of the
fixation nub contacting the guide, and the axis of the cylindrical
surface of the fixation nub inserted into the aperture(s) in the
bone would NOT be co-axial or collinear, but would instead be
parallel but offset by an distance proportional to the preload
desired. This offset embodiment of a fixation nub is herein
referred to as a "Cam Pin". As an example, FIGS. 83 and 84 show the
fixation nubs being inserted into two apertures formed in the
bone--lets say these are exactly 0.750 inches apart and 0.158
inches in diameter. In this example, the right most fixation nub
shown in FIG. 83 would be integrally formed as part of the cutting
guide, but the left most fixation nub is a Cam Pin capable of
swinging through an arc of 180 degrees (from a "9 O'clock"
direction to a "3 O'clock" direction) with an offset between its
guide engagement axis and its bone aperture engagement axis of
0.015 inches. With the cam pin oriented at its 9 O'clock direction,
the centerline of the integral fixation nub and the bone engagement
axis of the Cam Pin would be exactly 0.750 inches to allow for easy
insertion of the guide construct into the fixation apertures. Once
inserted, the guide construct is robustly fixed to the bone by
turning the Cam Pin to the 3 O'clock position creating a nominal
interference condition of 0.030 inches simultaneously preloading
the guide construct in tension and the bone in compression. As
minor deflection or distortion of the guide construct (and the
bone, but to a normally much lesser extent) will result, it may be
desirable to design the guide such that its desired configuration
is this preloaded or deflected or distorted shape and its nominal,
unloading condition is designed accordingly. This Cam Pin
embodiment of the present invention is applicable under any
circumstances where robust fixation between cutting constructs and
bone is desired to ensure accurate and/or precise bone cutting. It
should be noted that any degree of preload, in tension or
compression modes, could be sought and attained through simple
modification of the specific example cited above.
[0057] FIGS. 88 through 92 show a technique that will be described
as `guideless cutting` where properly prepared bone surfaces act as
the cutting guide. As shown in FIG. 88 and previously described in
the herein reference provisional applications, a modified forstner
style drill is used, under manual or surg nav guidance, to create
the Pivot Aperture and Pivot Reference Surface in the bone. The
bushing body is then engaged to these features as indicated in
comparing FIGS. 88 and 89 and manipulated to create the cut(s) for
attachment to the implant fixation surface(s) as represented in
FIGS. 91 and 92. This method is beneficially applied to the
application of tibia resection in creating the tibial cut shown in
FIG. 92, as well as any other bone surface resection
application.
[0058] FIGS. 93 through 98 represent a technique previously
described in the copending applications, but demonstrating
implementation of the side cutting drill embodiment of the present
invention for cutting tools. It is of interest to note that the
milling handle shown could further be guided by the PBR guides of
the present invention to further combine the accuracy and precision
benefits of PBR with the soft tissue protection characteristics of
tibially embedded femoral cutting tool. It should also be noted
that the side cutting drill with a curved cutting profile, similar
to that shown in FIG. 119, could also be used to attain cut
geometries possessing simultaneously curved or curvilinear cutting
profiles and cutting paths. In utilizing such, it would be critical
that the side to side location of the cutting profile of the
cutting tool be tightly controlled with respect to the desired side
to side location of the implant as the side to side location of the
implant would be dictated by the cut surfaces generated.
Alternatively, a cutting tool with a linear cutting profile, as
shown in FIG. 94, could be utilized to create cut surfaces with a
linear cutting profile and a curved cutting path, and then a second
cutter with a curved cutting profile could be used to create a
second, contiguous or noncontiguous, cut with a curved cutting
profile and/or path whose mediolateral location was closely
controlled to result in proper fit and location of the prosthesis
attached to said cut surfaces. It should be noted that the cutting
path of the second cutter could be located within a single plane,
such as for a bilateral femoral component design, or could be
curvilinearly divergent from the plane containing the cutting path
of the first cut surface. This would be useful for unilateral
femoral component designs (ones which require separate left and
right femoral implants) so as to allow for the implant design to
reflect out of plane patellofemoral kinematics and/or out of plane
tibiofemoral kinematics most accurately. Interestingly, this
embodiment of kinematic resection style resection could be modified
to allow the cutting tool to be directly or indirectly linked to
the movement of the patella with respect to the femur, or directly
connected to the patella, to enable cutting of patellofemoral
articular surfaces on the femur while moving the tibia and patella
through ranges of motion about the tibia. The embodiments of
cutting tools for use in attaining this include curvilinear end
cutting mills or face cutters, side cutting drills with linear or
non-linear cutting profiles, and other cutting tools capable of
cutting the femur while engaged, directly or indirectly, to the
patella. The side-to-side location of such cutters could be
determined by engagement or adjustment with respect to a PBR or
other guide, or simply by the natural kinematic path of the patella
about the femur during flexion-extension of the knee joint.
FIGS. 99 Through 112
[0059] FIGS. 99 through 127 generally represent prosthesis and
prosthesis fixation feature embodiments for use with the PBR
embodiments of the present invention. While there are particular
advantages to these implant prosthesis, it will also be recognized
that conventional implant prothesis or implant prosthesis of
alternate designs can also be used with the PBR embodiments of the
present invention.
[0060] FIGS. 99 through 102 show representations of a tongue in
groove fixation feature applied to a Unicondylar femoral component
enabling anterior insertion of one tongue element into a `t-slot`
style groove formed in bone and a progressively increasing press
fit obtained by forcing the implant posteriorly, as is represented
in comparing FIGS. 99 and 100. The t-slot feature, or groove,
formed in the femur is easily formed by, in one embodiment,
providing a trial component possessing a contoured groove and slot
for guiding a t-slot cutter along its length. Such a contour groove
would be responsible for controlling the depth of the t-slot in the
bone with respect to the cut surface to which the implant fixation
surface is attached, while the slot in the trial would dictate the
mediolateral location of the t-slot style groove. It is likely
necessary to include an aperture in the slot and/or contour groove
in the trial component to allow for insertion and plunging of the
wider T cutting surfaces prior to sweeping.
[0061] Alternatively, FIGS. 103 through 112 represent combinations
of finned and/or crosspinned implants. It should be noted that the
AP Fin Profile of the fin may be linear as shown in FIG. 106 (in
other words, the fin may be may be planar), or it could be slightly
tapered to achieve an interference fit with the walls of the groove
as the implant fixation surfaces are forced into contact with the
cut surfaces to which they are mated (see FIGS. 107 through 109),
or in could be curved as looked at from the viewpoint of FIG. 106
to further provide stability of fixation. Interestingly, the
fixation aperture created to fix a cutting guide to the bone could
be utilized to cross pin a flange or fin of a femoral prosthesis.
It should be noted that although the embodiment shown is a
Unicondylar femoral prosthesis, this concept could be applied to
tibial, femoral, or patellofemoral prostheses in any application,
or in other joint, trauma, spine, or oncology procedures, as is
generally represented in FIGS. 120 through 127. In FIGS. 105
through 112, a tapered pin is used to engage the cross pin hole in
the fin of the prosthesis. The tapered pin may be utilized to
facilitate a resulting press fit between the pin and the fixation
surfaces of the implant and/or ease of introducing the pin into the
hole in the fin. The pin could be of any known material, but
resorbable materials are especially interesting in as they are
`consumed` by the body leaving minimal hardware within the body
after a fairly predictable amount of time has passed. PLA/PGA
compositions, Tricalcium Phosphate, allograft and autograft bone,
bone substitutes, and the aforementioned slurry type compositions
may serve well. Alternatively, bone cement or other liquid or
semi-liquid material may be injected into the portals/apertures to
achieve intimate interdigitation, and the crosspins optionally
inserted thereafter, but prior to complete hardening or curing.
Alternatively, the crosspin(s) could be hollow with radially
extending holes allowing the pins to be inserted and then have bone
cement injected into them and up under the implant. Alternatively,
the cross pin could be threaded to engage threads in the fin, or to
engage the bone (both for short term stability and to facilitate
removal) or both. These embodiments hold significant promise in
both providing for intraoperatively stable cemented or cementless
fixation as well as facilitating long term biological ingrowth. It
should be noted that the use of multiple holes, pins, and apertures
in the prosthesis could be used and that the holes in the bone need
not be fixation holes to which guides are attached. Also it should
be noted the condylar sections, and patellofemoral sections of the
implant could be wholly separate, modularly joined, be composed of
a dual condylar prosthesis and separate patellofemoral prosthesis,
or any combination of the above. Although the bone/implant
interface shown is curved in two planes, these concepts apply to
implants with 3 planar curved geometry (where the cutting path and
cutting profiles of the resected surface geometry and therefore the
fixation surface geometry do not remain in two planes through the
entirety of the cutting path, or where the cutting path is
contained within multiple or single curved surfaces), entirely
planar geometries, or anything in between.
[0062] FIGS. 107 through 112 demonstrate another embodiment of an
implant prosthesis for use with the present invention allowing for
benefits well above and beyond those of the prior art. This will be
referred to herein as a BMO Prosthesis or BMO Cortical type implant
(Biomechanical Optimization Prosthesis). This embodiment has
several applications. For instance, if the resected surfaces are
going to vary significantly from the fixation surface geometries,
as may be seen in unguided kinematic resection, it may be
advantageous to implement fixation surface geometries that can
conform to variation in resection geometry. Most implant materials
in joint replacement are rigid, and that their rigidity is a
desirable characteristic for achieving stable fixation. In the case
of surface replacement, however, the present invention recognizes
that this is not necessarily the case. Very thin (less than 3 mm
thick, probably closer to a range of 1.5 to 0.01 mm thick) sections
of many metals, including implant grade metals and alloys cobalt
chrome, titanium, zirconium, and liquid metal, can be processed
into very thin forms capable of conforming to variations in the
resected surface and yet still have bearing surfaces that are
highly polished and provide significant contact area, where
desirable, for bearing against the bearing or articular surfaces of
the opposing implant. The construct or prosthesis resulting from
applying this concept to a femoral component in Unicondylar knee
replacement may start out being a 1'' wide be 3'' long strip of 1.5
mm thick material curved in a manner to generally look like the
curved cutting path and curved cutting profile of a natural,
healthy femur. A process such as Tecotex from Viasys Healthcare of
Wilmington, Mass. could be used to remove material from the strip
down to a nominal thickness of perhaps 0.1 mm thick (or other
thickness determined optimal via investigation) while leaving
protruding `hooks` (almost like the hook and eye concept of Velcro)
emerging from the thin fixation surface to engage the bone. One or
more fins could be attached or be a continuous part of this
construct as shown in FIG. 107. During insertion, the anterior most
cross pin could lock that portion of the prosthesis in place, then
the prosthesis could be wrapped around the remaining, more
posteriorly resected surfaces and the posterior cross pin inserted
(see FIG. 111). Alternatively, the fins could be located about the
periphery of the articular surfaces of the condyle in the form of
tabs and the cross pins or screws or tapered dowels, etc. known in
the art inserted through holes in the tabs and into bone to fix the
Cortical implant. The combination of fins and tabs may also be
useful. In using the tabs it is critical to keep all features of
the implanted device ultralow profile to avoid irritating the
surrounding soft tissues (perhaps creating recesses in the bone
underlying the tabs would be desirable to allow for a form of
countersinking of the tabs and/or the pins or screws or other
fixation devices). The flexibility of the implant would allow it to
conform to the resection surface and the stability of the crosspin
fixation would assist in reducing interfacial micromotion known to
inhibit bone ingrowth and fixation (this concept could be used with
PMMA, but it would be desirable to avoid the tissue necrosis and
bone preservation for revisional issues associated with the use of
bone cement if the patients health/comorbidities/indications
allow). This kind of implant could have some very interesting
clinical benefits beyond simple bone preservation. Given how well
this kind of implant would impart load to underlying bone, thus
avoiding stress shielding, it is possible not only to promote
healthy bone ingrowth into and around the interfacial features, but
the bearing contact and strains/stresses imparted to the bone could
motivate the bone to change its shape (and therefore the shape of
the implant--its flexible, remember?) to ideally conform to the
tibial component bearing surface such that bearing stresses are
carried through the broadest desirable contact area Oust like
modeling/remodeling in a healthy unmodified joint).
[0063] FIGS. 113 through 115 are an embodiment of the present
invention that may prove to be a very usefully alternative to
conventional rectilinear based referencing techniques. In essence,
conventional alignment techniques, once having established
appropriate flexion extension angulation and varus valgus
angulation of desired implant location, reference the anterior
cortex, distal most femoral condylar surface, and posterior most
condylar surface (indicated in FIG. 114 by stars) to dictate the
anterior posterior location, proximal distal location (otherwise
known as distal resection depth), and appropriate implant size in
determining the `perfect` location and orientation for the
appropriately sized implant (mediolateral location is normally
`eyeballed` by comparison of some visual reference of the
mediolateral border surrounding the distal cut surface and some
form of visual guide reference). These conventional techniques fail
to directly reference the distinctly different anatomic bone
features which dictate the performance of distinctly separate, but
functionally interrelated, kinematic phenomena, and they also
attempt to reference curvilinear articular surfaces by way of
rectilinear approximations. The embodiment of the present invention
is an alternative alignment technique with an object to overcome
the errors inherent in prior art. As shown in FIG. 115, the femur
possesses two distinct kinematic features and functions that lend
themselves to physical referencing; the patellofemoral articular
surface and the tibiofemoral articular surfaces, both of which are
curved, more specifically these surfaces represent logarithmic
curves. The one codependency between the two articular functions,
and therefore any geometric approximation made of them in
referencing, is that they must allow for smooth kinematically
appropriate articulation of the patella as it passes from its
articulation with the trochlear groove (shown in blue in FIG. 115)
to its articulation with intercondylar surfaces between the femoral
condyles (shown in red in FIG. 115). Thus, knowing that three
points define an arc and may be used to approximate a curve or
sections of a curve, what is proposed is to use a referencing
device which contacts at least one femoral condyle at three points
to determine both an approximation of arc radius and centerpoint
location, while independently or simultaneously referencing the
trochlear groove at three points to determine both an approximation
of arc radius and centerpoint location. The referencing system
would further need to provide for the need of the articular
surfaces of the trochlear articular surfaces to smoothly transition
to those of the intercondylar surfaces. Armed with this
information, a surgeon may most appropriately determine appropriate
implant location and orientation. This embodiment of the present
invention is especially useful in determining the proper location,
orientation, and implant size for the modular tricompartment
components shown in FIGS. 120 through 124, the non-modular implants
shown in FIGS. 125 through 127, and standard implants where the
appropriate size, location, and orientation would be determined by
that which best mimics existing articular bone surfaces thus
resulting in optimal postoperative kinematic function. FIG. 123
represents one method of fixing the patellofemoral implant with
respect to the condylar implant(s) so as to maintain smooth
transitional articulation. It should be noted that this crosspin
method of interconnecting the separate components could be
augmented by tongue and groove interlocking between the medial side
of the condylar component shown and the lateral side of the
patellofemoral component shown. What is critical is that the
transition between the patellofemoral component and the condylar
component surfaces responsible for patellofemoral articulation are
and remain tangent at least one point. FIGS. 128 and 129 represent
an alignment guide that could be easily modified to accomplish the
aforementioned 3 point referencing by addition or inclusion of
dedicated or modular referencing means.
[0064] FIG. 119 is a graphical representation of an offset power
input for a milling handle embodiment of the present invention. It
should be noted that the mechanism represented by the yellow
lines/arcs could be a chain, belt, spur gear, or other rotary power
transmission linkage. This allows for a milling handle design that
allows for the distal ends of the arms to be deeply inserted into a
wound without the drive input displacing soft tissue (as somewhat
shown in FIG. 71).
[0065] FIG. 130 represents a distal femur with the cuts shown for
fixation to a conventional total condylar implant with the border
of said cuts shown in black.
FIGS. 131 Through 146
[0066] FIGS. 131 through 146 show embodiments of the present
invention for cutting the distal and posterior areas of the
femur.
[0067] FIGS. 131 and 132 show an embodiment of the present
invention constituting an improved oscillating saw design. As
shown, this design possesses cutting teeth not only on the leading
edge as is commonly known in the art, but also on an adjacent
surface allowing the saw to cut both while plunging in a direction
parallel its long axis and normal to its long axis. FIGS. 133
through 134 show this in use with a cutting guide in cutting the
femur. It should be noted that the two smoother areas surrounding
the cutting teeth of the saw are intended for bearing contact with
a guide, but that bushings, or bearings could be added to
facilitate ease of use and avoidance of debris generation.
[0068] FIGS. 136 through 146 show an alternative cutting means. The
small cutting tool best shown in FIG. 136 is a small diameter
(0.188 inches to 0.040 inches) side cutting drill, optionally for
use in conjunction with a milling handle (not shown). As shown in
these figures, a robustly guided cutting tool can be used to cut
both condyles when guided by a guide either straddling only one
condyle (as shown), or fixed to the medial side of the lateral
condyle and the lateral side of the medial condyle. These
embodiments may also be applied to cutting of only one condyle, and
the cutting path of the guide shown modified to allow for standard
or improved Unicondylar use. Also shown, the manipulation of the
cutting tool while guided by a PBR guide can include plunging,
sweeping and pivotally sweeping manipulations in completing the
desired cuts. Once these cuts have been completed, or partially
completed and finished by other means, as shown in FIGS. 145 and
146, alternate methods may be employed to complete the remaining
cuts. It should be noted that methods allowing for the resection of
the posterior femoral condyles and/or the distal femoral condyles
in conjunction with the proximal tibia already having been cut,
provide for a phenomenal amount of laxity of the soft tissues
surrounding the joint allowing for a surgeon to more easily
complete cutting of the anterior cut and anterior chamfer cut.
[0069] 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.
* * * * *