U.S. patent application number 13/942144 was filed with the patent office on 2014-01-16 for patient match instrument.
This patent application is currently assigned to Smith & Nephew, Inc.. The applicant listed for this patent is Michael J. JACKSON, Eric S. KENNEDY, Brian W. MCKINNON, Zachary C. WILKINSON, Randy C. WINEBARGER. Invention is credited to Michael J. JACKSON, Eric S. KENNEDY, Brian W. MCKINNON, Zachary C. WILKINSON, Randy C. WINEBARGER.
Application Number | 20140018813 13/942144 |
Document ID | / |
Family ID | 49914615 |
Filed Date | 2014-01-16 |
United States Patent
Application |
20140018813 |
Kind Code |
A1 |
MCKINNON; Brian W. ; et
al. |
January 16, 2014 |
PATIENT MATCH INSTRUMENT
Abstract
A patient matched instrument for a patient's femur is disclosed.
The instrument includes a body having a cutting slot and a patient
matched surface that mates with the patient's trochlear groove, a
first leg portion extending from the body, a second leg portion
extending from the body; and each leg portion has a contacting pad
for tangential contact with the patient's femoral medial and
lateral condyles.
Inventors: |
MCKINNON; Brian W.;
(Bartlett, TN) ; KENNEDY; Eric S.; (Memphis,
TN) ; JACKSON; Michael J.; (Southaven, MS) ;
WINEBARGER; Randy C.; (Southaven, MS) ; WILKINSON;
Zachary C.; (Germantown, TN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MCKINNON; Brian W.
KENNEDY; Eric S.
JACKSON; Michael J.
WINEBARGER; Randy C.
WILKINSON; Zachary C. |
Bartlett
Memphis
Southaven
Southaven
Germantown |
TN
TN
MS
MS
TN |
US
US
US
US
US |
|
|
Assignee: |
Smith & Nephew, Inc.
Memphis
TN
|
Family ID: |
49914615 |
Appl. No.: |
13/942144 |
Filed: |
July 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61715562 |
Oct 18, 2012 |
|
|
|
61681440 |
Aug 9, 2012 |
|
|
|
61671758 |
Jul 15, 2012 |
|
|
|
Current U.S.
Class: |
606/88 |
Current CPC
Class: |
A61B 17/1764 20130101;
A61B 2034/108 20160201; A61B 17/155 20130101; A61B 2017/568
20130101 |
Class at
Publication: |
606/88 |
International
Class: |
A61B 17/15 20060101
A61B017/15 |
Claims
1. A patient matched instrument for a patient's femur having a
trochlear groove, a medial condyle, and a lateral condyle, the
instrument comprising: a. a body having a cutting slot and a
patient matched surface that mates with the patient's trochlear
groove; b. a first leg portion extending from the body; c. a second
leg portion extending from the body; and d. wherein each leg
portion has a contacting pad for tangential contact with the
patient's femoral medial and lateral condyles.
2. The instrument of claim 1, the body further comprising a visual
indicator.
3. The instrument of claim 1, the body further comprising a
window.
4. The instrument of claim 1, the body further comprising
apertures.
5. The instrument of claim 1, wherein each leg portion further
comprises at least one pin boss.
6. The instrument of claim 1, further comprising a guide.
7. The instrument of claim 1, wherein the patient matched surface
of the body has six boundary conditions.
8. The instrument of claim 1, wherein the first leg portion has a
different length from the second leg portion.
9. The instrument of claim 1, wherein the contacting pads are
substantially perpendicular to the mechanical axis.
10. The instrument of claim 1, wherein the contacting pads are
parallel to the cutting slot.
11. The instrument of claim 1, wherein the contacting pads contact
the femoral condyles at angle relative to the cutting slot and/or
the mechanical axis.
12. The instrument of claim 1, the body further comprising a
passage.
13. The instrument of claim 1, wherein the body includes at least
one cross-member.
14. The instrument of claim 1, wherein the body further comprises
an anterior ridge extension.
15. The instrument of claim 1, further comprising at least one
surface contact confirmation slot.
16. The instrument of claim 1, further comprising a distal trochlea
grip.
17. The instrument of claim 1, wherein each leg portion includes at
least one paddle.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/671,758, filed 15 Jul. 2012, of U.S. Provisional
Application No. 61/681,440, filed 9 Aug. 2012, and of U.S.
Provisional Application No. 61/715,562, filed 18 Oct. 2012. The
disclosure of each prior application is incorporated by reference
in its entirety.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to surgical
instruments and methods for the treatment of bones or joints, in
some instances surgical instruments that are matched to a
particular patient's anatomy, are described herein. Also described
are methods of designing and using such surgical instruments.
[0003] Conventional patient-matched instruments are provided with
large surfaces that are configured to conform to a patient's unique
anatomy. Successful surgical outcomes depend on the ability of
patient-matched instruments to provide a reproducible, "confident"
3D-fit between the patient-matched instrument and the anatomy that
they are designed to rest against. If there is any doubt by an end
user that a patient-matched instrument fits well upon repeated
engagement with a patient's unique anatomy, or if the instrument
appears to fit well with the patient's anatomy in multiple spatial
orientations with respect to the anatomy, the instrument is
typically discarded, and the surgery is carried out with the use of
conventional, non-patient specific instruments.
[0004] To date, at least some patient-matched surgical instruments
for use in total knee arthroplasty have employed anatomy-contacting
surfaces that are substantially "negatives" of distal femoral and
proximal tibial articular joint surfaces. The anatomy-contacting
surfaces are generally large surface areas that conform in a
continuous manner to substantial areas of a patient's anatomy. In
some instances, the custom surgical instruments are provided by
obtaining 3D image data of the patient's anatomy (e.g., via an MRI
scan), segmenting the 3D image data to clearly delineate surfaces
of the bony and/or cartilegeneous anatomy from surrounding tissues,
converting the segmented data to a computer model via CAD or other
software, performing one or more optional secondary processes
(e.g., smoothing functions), using a computer model to customize
one or more surfaces of an instrument to the patient's anatomy, and
manufacturing the custom instrument such that it is adapted to
conform to the patient's anatomy in a single spatial
orientation.
[0005] In at least some current practices, substantially all
portions of the joint anatomy shown in each 3D image data slice are
segmented and conventional patient-matched instruments are provided
with anatomy-contacting portions that contact substantially
continuous areas of the patient's anatomy. Such anatomy-contacting
portions have large continuous surface areas of contact with the
patient's bone and cartilage, and therefore, it is critical that
the engineers or automated programs creating the patient-matched
instruments maintain a high level of accuracy and precision
throughout each step of the entire segmentation process. Even if
only one or two points on anatomy-contacting surfaces of a
patient-matched instrument are inaccurate, misaligned, or otherwise
misrepresent the true unique anatomy of the patient, the
patient-matched instrument may not fit well, sit proud, teeter,
wobble, or may not fit at all. In such instances, an end user is
less likely to use the instrument. In many cases, poor
patient-matched instrument fit may be attributed to even a few
minor errors in the segmentation process.
SUMMARY OF THE INVENTION
[0006] The various embodiments of the present invention described
below and shown in the Figures provide a patient matched instrument
that is designed to provide improved repeatability and
reproducibility over the prior art. The patient matched instrument
includes a patient matched surfaces that mates with a patient' s
trochlear groove and two contacting pads for tangent contact with
the patient's femoral condyles. The patient matched instrument
incorporates design features that encourage consistent placement
and accurate placement.
[0007] Further areas of applicability of the invention will become
apparent from the detailed description provided hereinafter. It
should be understood that the detailed description and specific
examples, while indicating the particular embodiment of the
invention, are intended for purposes of illustration only and are
not intended to limit the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The accompanying drawings which is this case is a group of
sketches prepared by the inventor and, which are incorporated in
and form a part of the specification, illustrate the embodiments of
the invention and together with the written description serve to
explain the principles, characteristics, and features of the
invention. In the drawings:
[0009] FIG. 1 shows a side perspective view of a patient matched
instrument mounted on a left femur.
[0010] FIGS. 2A and 2B show an inferior-superior view of the
patient matched instrument of FIG. 1.
[0011] FIG. 3 shows an anterior-posterior view of the patient
matched instrument of FIG. 1.
[0012] FIG. 4 shows a bottom perspective view of the patient
matched instrument.
[0013] FIG. 5 shows a bottom view of the patient matched
instrument.
[0014] FIGS. 6A and 6B show a side view of two embodiments of the
patient matched instrument.
[0015] FIG. 7 is an exemplary illustration of a human right-side
femur attached to a tibia by the anterior and the posterior
cruciate ligaments.
[0016] FIG. 8 is an expanded view of a human right-side knee joint
in a bent position.
[0017] FIG. 9 illustrates the anterior trochlear sulcus which may
be used to determine the AP axis.
[0018] FIG. 10 illustrates an embodiment of the patient instrument
with a window to view the AP axis.
[0019] FIGS. 11a and 11b illustrate an embodiment with a grid
opening to view the AP axis.
[0020] FIGS. 12-13 illustrate an embodiment having an anterior
ridge extension.
[0021] FIGS. 14-19 illustrate an embodiment having surface contact
confirmation slots.
[0022] FIGS. 20-24 illustrate a distal trochlea notch grip.
[0023] FIG. 25 illustrates an embodiment of the patient matched
instrument having tangent contact paddles.
[0024] FIGS. 26 and 27 graphically illustrate the consistency and
accuracy provided by the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0025] The following description of the depicted embodiment(s) is
merely exemplary in nature and is in no way intended to limit the
invention, its application, or uses.
[0026] Embodiments of the present invention provide a patient
matched instrument that is designed to provide improved
repeatability and reproducibility over the prior art. FIG. 1
illustrates a patient matched instrument 200 placed on a femur 2.
The patient matched instrument 200 is used to make a distal cut in
knee arthroplasty. The patient matched instrument 200 includes a
body 202. A first leg portion 206 and a second leg portion 208
extend from the body 202. The body includes a cutting slot 210 and
one or more pin bosses 212 are located on each leg portion 206,208.
In some embodiments, the patient matched instrument 200 also
includes pin mounts 214. In use, the femur 2 is exposed via
surgical incision. The patient matched cutting block 200 is placed
on the femur 2 and located in a home position. Pins (not shown) are
inserted into the pin bosses 212. Pins may be inserted into the pin
mounts 214. A saw blade 4 (FIG. 2B) is reciprocated in the cutting
slot 210 to remove bone from a distal end of the femur 2.
[0027] In some embodiments, the patient matched instrument 200 may
include a visual indicator 216. In the depicted embodiment, the
visual indicator 216 is formed by a groove, however, the visual
indicator 216 also may be formed by other shapes or by other
methods, such as painting or printing. As an example, the visual
indicator 216 may align with the anterior-posterior (AP) axis or
Whiteside's line of the femur 2. As another example, the visual
indicator 216 may indicate the mechanical or anatomic axis of the
femur 2.
[0028] FIGS. 2A and 2B illustrate the patient matched instrument
200 mounted on the femur 2. The femur 2 has a medial condyle 106, a
lateral condyle 104, and an intercondylar notch 21. Optionally, the
patient matched instrument 200 may include a window 220. The window
220 allows an operator to see a saw blade 4 as it progresses in
making the distal cut. As an example, the saw blade 4 may be seen
in front of the intercondylar notch 21 between condylar portions
104,106 of the femur 2. In some embodiments, the patient matched
instrument 200 includes one or more apertures 222. The aperture 222
may take any shape. For example, the aperture 222 may be square,
rectangular, cylindrical, or trapezoidal. The patient matched
instrument 200 includes a front surface 204
[0029] The patient matched instrument 200 includes the first leg
portion 206 and the second leg portion 208. Each leg portion
206,208 includes one of the pin bosses 212. In some embodiments,
each leg portion 204, 206 extends anteriorly in front of each
condyle 104, 106. Each leg portion 206,208 may have a radiused face
224.
[0030] In some embodiments, the patient matched instrument 200
includes a guide 230. The guide 230 may be used to check for
general alignment. For example, the guide 230 may align with the
epicondylar axis, and a user may inspect the guide 230 compared to
the epicondylar axis to check for general alignment of the patient
matched instrument 200. The guide 230, if included, is also
functional as it connects the first leg portion 206 to the second
leg portion 208 for structural reinforcement. In the depicted
embodiment, the guide 230 is substantially square and has a
thickness of about 3 mm. Of course, other shapes, such as round,
are possible, and also other dimensions are possible. For example,
the guide 230 may have a cross-sectional diameter or width ranging
from about 2 mm to about 15 mm, with a preferred range of about 3
mm to about 6 mm.
[0031] As shown in FIG. 3, the patient matched instrument 200 may
include one or more additional fixation holes 236 to temporarily
affix the patient matched instrument 200 to the femur 2. In some
embodiments, the fixation hole 236 is angled relative to the
cutting slot 210. For example, the fixation hole 236 may be angled
from about 15 degrees to about 75 degrees. In the depicted
embodiment, the fixation hole 236 is angled at about 45 degrees
relative to the cutting slot 210.
[0032] FIG. 4 illustrates the patient matched instrument 200 having
a patient matched surface 240, a first contact pad 250, and a
second contact pad 252. The patient matched surface 240 may be
substantially defined by six boundary conditions 8, 10, 12, 14, 16,
and 18 (outlined in FIG. 4 for visibility). In general, the patient
matched surface 240 is custom-designed and manufactured to match
the shape of and mate with a portion of a patient's trochlear
groove. The first and second contact pads 250,252 are each
generally planar and formed on each respective leg portion 206,208.
The first and second contact pads 250,252 may be offset from one
another in an anterior-posterior direction for varus/valgus
constraint. The first and second contact pads are constructed and
arranged to contact the utmost distal portions of the condyles
104,106. Due to the nature in which imaging data is obtained (i.e.,
2 mm slices in a sagittal plane) and 3D bone anatomic models are
produced, the combination of the trochlear groove contact in
combination with the distal condyle contact provides a custom
cutting block is the highly reproducible and repeatable. As more
accurate data is available as to the utmost distal point of each
condyle 104, 106, in some embodiments the contact pads 250,252 are
the primary references and any other contact portion, such as in
the trochlear groove, is secondary. This may be of significance for
geometric tolerancing. Each of the first and second contact pads
250,252 may provide line contact, area contact, a plurality of
contact points, or a single point of contact.
[0033] As best seen in FIG. 5, the leg portions 206, 208 may be of
different lengths. Also, the boundary 8 (described in greater
detail below) has a straight edge appearance but need not have
one.
[0034] In the embodiment depicted in FIG. 6A, the first and second
contact pads 250, 252 are generally parallel to the cutting slot
210 and/or substantially perpendicular to the mechanical axis.
Those of ordinary skill in the art would understand that other
arrangements are possible. For example, as shown in FIG. 6B, the
first and second contact pads may be designed to contact other
and/or additional portions of condyles 104, 106 at an angle
relative to the cutting slot 210 and/or the mechanical axis.
[0035] FIGS. 7 and 8 show exemplary views of a normal, intact knee
joint. By way of background, a human knee joint includes two
cruciate ligaments which are located in the center of the knee
joint. As shown in FIG. 8, these two ligaments, referred to in the
art as the anterior cruciate ligament (ACL) 22 and the posterior
cruciate ligament (PCL) 24, are primary stabilizing ligaments of
the knee. The ACL 22 attaches at its distal end 26 to the tibia 30,
and passes obliquely upward into the inner and back part 32 of the
lateral condyle 104 of the femur 2 for attachment at the proximal
end. Attachment of the ACL 22 to the femur 2 stabilizes the knee
joint along the anterior-posterior direction and prevents the femur
2 from sliding backwards on the tibia 30 (or the tibia from sliding
forward on the femur).
[0036] In some embodiments, the first boundary condition 8 of the
patient matched surface may be designed to not extend far back to
impinge upon the cruciate attachments or the ligaments themselves.
Therefore, the first boundary condition of a patient matched
surface may be defined to be about 2 to about 13 mm from the point
of attachment of the ACL 22 or the PCL 24 to the patient's femur 2.
More specifically, as illustrated in FIG. 8, the first boundary
condition 8 may be from about 3 mm to about 6 mm from the point of
attachment 20 of the ACL 22 or PCL 24. In other words, there is
about 2 mm to about 13 mm distance between the first boundary
condition 8 and the attachment 20 of the ACL 22 or PCL 24.
Alternatively, the first boundary condition of a patient matched
surface 8 is within the intercondylar notch 21 but of a sufficient
distance above where the ACL 22 or PCL 24 exits.
[0037] The second boundary condition 10 may be defined
approximately at or near a superior edge 100 of an end of natural
cartilage 102. In some embodiments, the patient matched surface 240
may extend slightly over the superior edge 100 to "hook" upon it.
In other words, the second boundary condition 10 may have a lip to
engage the superior edge 100. The third boundary condition 12 may
be approximately at a top ridge of the lateral condyle 104. The
fourth boundary condition 14 may be approximately at a top ridge of
the medial condyle 106. The fifth and sixth boundar condition 16,
18 are angled upward and away from the condyles 104, 106 to provide
clearance. The four boundary conditions 8, 10, 12, 14 as described
above, may substantially define the perimeter or outer edges of the
patient matched surface 240. However, the patient matched surface
240 need not be defined by any one of the four boundary conditions.
Alternatively, the patient matched surface may be defined by any
one of or any combination of the four boundary conditions. Of
course, the perimeter or outer edges of individual patient matched
surfaces may differ depending on the unique anatomic
characteristics of an individual patient's femur.
[0038] Alternatively, a portion of the perimeter of the patient
matched surface 240 may be defined by intersecting the cutting
plane with a trochlear groove of the anatomic model. The resulting
edge provides a general definition of the boundary condition edge
8. In other words, the patient matched surface 240 may be defined
by intersecting boundaries of the anatomic model and the cutting
plane. For example, the patient matched surface 240 is defined in a
CAD model of the patient's anatomy by creating the distal cutting
plane of the femur and defining the edge between cutting plane and
the trochlear groove of the anatomic model.
[0039] As best seen in FIG. 9, a user may use points P on the femur
2 to generate a line W. Line W is indicative of the AP axis, a
feature commonly used as a reference in knee surgery. As an
example, a user may use a bovie to generate the points P and the
line W.
[0040] FIG. 10 illustrates a patient matched instrument 300. The
patient matched instrument has a passage 310. The passage 310 is
customized for each individual patient. For example, an engineer or
automated software landmarks low points of an anterior sulcus by
creating points on a bone model created from imaging data in a
modeling or imaging software. In one particular embodiment from
about 4 to about 10 points are created on the bone model. The
created points are connected with a line in the modeling or imaging
software. This line forms the midline of the positive or negative
AP line feature on the patient matched instrument. When the patient
matched instrument is placed on the bone, the user can view the AP
axis through the passage 310 for visual confirmation as to correct
placement. Alternatively, the user can use the passage to trace the
AP axis for use as a guide when the patient matched instrument is
placed on the bone.
[0041] FIG. 11a illustrates a patient matched instrument 400. The
patient matched instrument has a first cross-member 410, a second
cross-member 420, and a third cross-member 430. The patient matched
instrument 400 could have additional or fewer cross-members. The
cross-members 410, 420, 430 form openings 450. The user can view
the AP axis along the first cross-member 410 for visual
confirmation as to correct placement. Additionally, a user can use
openings 450 to visualize and confirm that cross-members 420,430
contact bone.
[0042] FIG. 11b illustrates a variation of the embodiment shown in
FIG. 11a. In the depicted embodiment, the patient matched
instrument 400' has a first cross member formed by a lateral member
461 and a medial member 463. The lateral and medial members 461,
461 are spaced apart to form a space 465. The user can view the AP
axis through the space 465 for visual confirmation as to correct
placement. Alternatively, the user can use the space 465 to trace
the AP axis for use as a guide.
[0043] In some embodiments, the patient matched instrument 400 may
include an anterior ridge extension 460. The anterior ridge
extension 460 includes a first ear 462 and a second ear 464. In
some embodiments, the anterior ridge extension 460 may include only
the first ear 462 or the second ear 464. The anterior ridge
extension 460 creates additional contact along both medial and
lateral portions of the femoral anterior ridge.
[0044] Alternative embodiments of the anterior ridge extension are
shown in FIGS. 12 and 13. In the depicted embodiment, the patient
matched instrument 500 includes an anterior ridge extension 510.
The anterior ridge extension 510 includes a first ear 514 and a
second ear 512. In some embodiments, the anterior ridge extension
510 may include only the first ear 514 or the second ear 512. The
anterior ridge extension 510 creates additional contact along both
medial and lateral portions of the femoral anterior ridge.
[0045] FIGS. 14-19 an embodiment having surface contact
confirmation slots that help determine proper placement of a
patient matched instrument as a visual check to ensure correct
placement. In the depicted embodiment, the patient matched
instrument 600 has a medial surface contact confirmation slot 610
and a lateral surface contact confirmation slot 612. The slots 610,
612 cut out of the distal paddles of the patient matched instrument
denote a point that the distal femur makes contact with a tangent
surface of the patient matched instrument. A user, such as surgeon,
may place the patient matched instrument on the femur, view the
patient matched instrument laterally and medially to verify that
the slot outline lines up with the point where the patient matched
instrument and bone meet. Although slots are shown in the depicted
embodiment, those having ordinary skill in the art would understand
that the confirmation feature could be negative (such as the slot)
or positive. Further, instead of slots, other shapes, such as
arrows or circles, may be used.
[0046] FIGS. 17-19 illustrate a variation of the embodiment shown
in FIGS. 14-16. In the depicted embodiment, the patient matched
instrument 650 includes not only medial and lateral slots 652, 658,
but also distal slots 654, 656. In some embodiments, all or some of
the slots 652, 654, 656, 658 may include color to increase
visibility. For example, some of the slots may be colored red or
yellow. The slots 652, 654, 656, 658 are sized and shaped to line
up with only one point. A user view the femur posteriorly and
sagittally to confirm the slots where the patient matched
instrument contacts bone.
[0047] FIGS. 20-24 illustrate a distal trochlea notch grip. The
notch grip is a portion of the patient matched instrument that is
extended to contact and conform to the distal trochlea. In a first
embodiment, the patient matched instrument 700 includes a distal
trochlea notch grip 712. In some embodiments, the patient matched
instrument 700' has a frangible distal trochlea grip 712' that is
constructed and arranged to break at an area 714. The part is
frangible after fixation to eliminate interference with resection.
In some embodiments, the distal trochlea notch grip is combined
with the anterior ridge extension to aid in capturing the patient
matched instrument in two relatively opposed locations.
[0048] The second embodiment, depicted in FIGS. 23-24, illustrates
a patient matched instrument 750 with a somewhat wider and larger
distal trochlea notch grip 752 than the one shown in FIGS. 20-22.
As with the first embodiment, the distal trochlea notch grip 752
may be frangible in some instances.
[0049] FIG. 25 illustrates an embodiment of the patient matched
instrument 800 having paddles 810. The paddles 810 provide angled,
tangent contact with each femoral condyle to provide additional
rotational stability.
[0050] FIGS. 26 and 27 graphically illustrate results of lab
testing of the disclosed embodiments. The protocol consisted of
three operators performing three to five placement of each block
design on a cadaver bone. Three degrees of freedom were measured
with a computer assisted surgery (CAS) system for each individual
placement. Specifically, these were: (1) varus/valgus rotation
angle; (2) flexion/extension rotation angle; and (3)
internal/external rotation angle. The standard deviation of all
placements for a given block design was calculated for each degree
of freedom. FIGS. 26 and 27 illustrate that the present invention
(named "PFJ+Points" on the graphs) had the lowest standard
deviation of all tested devices. Further, FIG. 27 illustrates that
reducing the PFJ contact portion and replacing it with a somewhat
truncated contact with several points (named "Points" on the
graphs) was less than optimal but not necessarily unacceptable.
There may be a threshold where the area/point contact trade off
becomes "even" (as determined by the constraint provided), and as
such it may be best described as a "point density" (points per unit
area) rather than a specific number of points that is optimal.
Also, that point density could vary over the surface. In some
embodiments, full PFJ-area contact may be replaced by a range of
point contact densities that are functionally equivalent or
superior to full area contact. As an example, the range may be
about 5 points/cm 2 to about 30 points/cm 2.
[0051] The term "substantially" as used herein may be applied to
modify any quantitative representation which could permissibly vary
without resulting in a change in the basic function to which it is
related. For example, the contacting pads are disclosed as being
substantially perpendicular to the mechanical axis and may
permissibly have some variation from being truly perpendicular and
still be within the scope of the invention if the function of the
contacting pads are not materially altered.
[0052] In view of the foregoing, it will be seen that the several
advantages of the invention are achieved and attained.
[0053] The embodiments were chosen and described in order to best
explain the principles of the invention and its practical
application to thereby enable others skilled in the art to best
utilize the invention in various embodiments and with various
modifications as are suited to the particular use contemplated.
[0054] As various modifications could be made in the constructions
and methods herein described and illustrated without departing from
the scope of the invention, it is intended that all matter
contained in the foregoing description or shown in the accompanying
drawings shall be interpreted as illustrative rather than limiting.
For example, while FIG. 1 illustrates pin bosses that receive pins
other structure and/or methods may be used to temporarily affix the
patient matched instrument to the femur. Thus, the breadth and
scope of the present invention should not be limited by any of the
above-described exemplary embodiments, but should be defined only
in accordance with the following claims appended hereto and their
equivalents.
* * * * *