U.S. patent application number 11/472610 was filed with the patent office on 2008-01-17 for cutting block for bone resection.
This patent application is currently assigned to Howmedica Osteonics Corp.. Invention is credited to Stuart L. Axelson.
Application Number | 20080015602 11/472610 |
Document ID | / |
Family ID | 38950216 |
Filed Date | 2008-01-17 |
United States Patent
Application |
20080015602 |
Kind Code |
A1 |
Axelson; Stuart L. |
January 17, 2008 |
Cutting block for bone resection
Abstract
A cutting block having a base, and a top connected to the base
via four walls is disclosed. Each wall has an outwardly facing
surface to guide a cutting tool. Each wall also has an attachment
hole where a tracker may be attached. The cutting block is floated
on the bone using the navigation system to position it at correct
locations for the bone resection. After correctly locating the
cutting block for each required cut, cutting block is fixed to the
bone using pins and the bone resected. Same cutting block is
suitable for resection of bone for installation of any size
prosthetic device. For certain resections, the rotation angle may
be mechanically set and need not be navigated.
Inventors: |
Axelson; Stuart L.;
(Succasunna, NJ) |
Correspondence
Address: |
LERNER, DAVID, LITTENBERG,;KRUMHOLZ & MENTLIK
600 SOUTH AVENUE WEST
WESTFIELD
NJ
07090
US
|
Assignee: |
Howmedica Osteonics Corp.
Mahwah
NJ
|
Family ID: |
38950216 |
Appl. No.: |
11/472610 |
Filed: |
June 22, 2006 |
Current U.S.
Class: |
606/87 |
Current CPC
Class: |
A61B 90/94 20160201;
A61B 17/155 20130101; A61B 2034/2068 20160201 |
Class at
Publication: |
606/87 |
International
Class: |
A61F 5/00 20060101
A61F005/00 |
Claims
1. A cutting block for bone resection, comprising: a base; a top; a
first outwardly facing surface extending between the base and the
top, the first outwardly facing surface providing a first guiding
surface for the resection of anterior surface of the femur; a
second outwardly facing surface extending between the base and the
top, the second outwardly facing surface providing a second guiding
surface for the resection of the posterior and the distal surface
of the femur; a third outwardly facing surface extending between
the base and the top, the third outwardly facing surface providing
a third guiding surface for making the anterior chamfer cut on the
femur; and a fourth outwardly facing surface extending between the
base and the top, the fourth outwardly facing surface providing a
fourth guiding surface for making the posterior chamfer cut on the
femur.
2. The cutting block of claim 1, further comprising: at least two
holes extending from the top to the base.
3. The cutting block of claim 2, further comprising: a first slot
and a second slot, the first and the second slot extending through
the thickness of the cutting block and being parallel to each
other; and a third slot and a fourth slot, the third and the fourth
slot extending through the thickness of the block and being
parallel to each other and orthogonal to the first and the second
slot.
4. The cutting block of claim 2, further comprising: at least one
mounting means for mounting a tracker.
5. The cutting block of claim 4, wherein the mounting means is an
opening on one of the first, second, third or fourth outwardly
facing surface.
6. The cutting block of claim 5, further comprising: a tracker
mounted in the mounting means.
7. The cutting block of claim 5, wherein the first outwardly facing
surface extending between the base and the top is angled with
respect to the base.
8. The cutting block of claim 7, wherein the angle matches an angle
on a prosthetic device.
9. The cutting block of claim 8, wherein the bone being resected is
a femur.
10. A cutting block for bone resection, comprising: a base; a top;
and four outwardly facing surfaces connecting the base and the top,
each of the four outwardly facing surfaces providing at least one
guiding surface for making at least one bone resection; wherein one
size cutting block can be used for femoral resection suitable for
any size femoral prosthesis.
11. The cutting block of claim 10, further comprising: at least two
holes extending from the top to the base.
12. The cutting block of claim 11, further comprising: a first slot
and a second slot, the first and the second slot extending through
the thickness of the cutting block and being parallel to each
other; and a third slot and a fourth slot, the third and the fourth
slot extending through the thickness of the block and being
parallel to each other and orthogonal to the first and the second
slot.
13. The cutting block of claim 11, further comprising: at least one
mounting means for mounting a tracker.
14. The cutting block of claim 13, wherein the mounting means is an
opening on one of the four outwardly facing surfaces.
15. The cutting block of claim 14, further comprising: a tracker
mounted in the mounting means.
16. The cutting block of claim 14, wherein one of the four
outwardly facing surfaces extending between the base and the top is
angled with respect to the base.
17. The cutting block of claim 16, wherein the angle matches an
angle on a prosthetic device.
18. The cutting block of claim 17, wherein the bone being resected
is a femur.
19. A cutting block for femoral resection, comprising: a base; a
top; and four outwardly facing surfaces connecting the base and the
top, each of the four outwardly facing surfaces providing at least
one guiding surface for making at least one of the anterior,
posterior, distal, anterior chamfer and posterior chamfer cuts;
wherein the outwardly facing surface providing the guiding surface
for the anterior cut is angled with respect to the base, the angle
matching the anterior flange angle of a femoral prosthesis.
20. The cutting block of claim 19, further comprising: at least two
holes extending from the top to the base.
21. The cutting block of claim 20, further comprising: a first slot
and a second slot, the first and the second slot extending through
the thickness of the cutting block and being parallel to each
other; and a third slot and a fourth slot, the third and the fourth
slot extending through the thickness of the block and being
parallel to each other and orthogonal to the first and the second
slot.
22. The cutting block of claim 20, further comprising: at least one
mounting means for mounting a tracker.
23. The cutting block of claim 22, wherein the mounting means is an
opening on one of the four outwardly facing surfaces.
24. The cutting block of claim 23, further comprising: a tracker
mounted in the mounting means.
25. A cutting block for femoral resection, comprising: a base; a
top; a first outwardly facing surface extending between the base
and the top, the first outwardly facing surface providing a first
guiding surface for the resection of anterior surface of the femur;
a second outwardly facing surface extending between the base and
the top, the second outwardly facing surface providing a second
guiding surface for the resection of the posterior and the distal
surface of the femur; a third outwardly facing surface extending
between the base and the top, the third outwardly facing surface
providing a third guiding surface for making the anterior chamfer
cut on the femur; and a fourth outwardly facing surface extending
between the base and the top, the fourth outwardly facing surface
providing a fourth guiding surface for making the posterior chamfer
cut on the femur; wherein the first outwardly facing surface is
angled with respect to the base.
26. The cutting block of claim 25, further comprising: at least two
holes extending from the top to the base.
27. The cutting block of claim 26, further comprising: a first slot
and a second slot, the first and the second slot extending through
the thickness of the cutting block and being parallel to each
other; and a third slot and a fourth slot, the third and the fourth
slot extending through the thickness of the block and being
parallel to each other and orthogonal to the first and the second
slot.
28. The cutting block of claim 26, further comprising: at least one
mounting means for mounting a tracker.
29. The cutting block of claim 28, wherein the mounting means is an
opening on one of the four outwardly facing surfaces.
30. The cutting block of claim 29, further comprising: a tracker
mounted in the mounting means.
31. The cutting block of claim 30, wherein the angle formed by the
first outwardly facing surface with respect to the base matches an
angle on a prosthetic device.
32. A cutting block for femoral resection, comprising: a base; a
top; a first outwardly facing surface extending between the base
and the top, the first outwardly facing surface providing a first
guiding surface for the resection of anterior surface of the femur;
a second outwardly facing surface extending between the base and
the top, the second outwardly facing surface providing a second
guiding surface for the resection of the posterior and the distal
surface of the femur; and a third outwardly facing surface
extending between the base and the top, the third outwardly facing
surface providing a third guiding surface for making the anterior
chamfer cut and the posterior chamfer cut on the femur; wherein one
size cutting block can be used for femoral resection suitable for
any size femoral prosthesis.
33. The cutting block of claim 32, further comprising: at least two
holes extending from the top to the base.
34. The cutting block of claim 33, further comprising: a first slot
and a second slot, the first and the second slot extending through
the thickness of the cutting block and being parallel to each
other; and a third slot and a fourth slot, the third and the fourth
slot extending through the thickness of the block and being
parallel to each other and orthogonal to the first and the second
slot.
35. The cutting block of claim 33, further comprising: at least one
mounting means for mounting a tracker.
36. The cutting block of claim 35, wherein the mounting means is an
opening on one of the first, second or third outwardly facing
surface.
37. The cutting block of claim 36, further comprising: a tracker
mounted in the mounting means.
38. The cutting block of claim 36, wherein the first outwardly
facing surface extending between the base and the top is angled
with respect to the base.
39. The cutting block of claim 38, wherein the angle matches an
angle on a prosthetic device.
40. A cutting block for femoral resection, comprising: a base; a
top; a first outwardly facing surface extending between the base
and the top, the first outwardly facing surface providing a first
guiding surface for the resection of anterior surface of the femur;
an angle formed between the first outwardly facing surface and the
base, the angle matching the anterior flange angle of a femoral
prosthesis to be implanted; a second outwardly facing surface
extending between the base and the top, the second outwardly facing
surface providing a second guiding surface for the resection of the
posterior and the distal surface of the femur; a third outwardly
facing surface extending between the base and the top, the third
outwardly facing surface providing a third guiding surface for
making the anterior chamfer cut on the femur; and a fourth
outwardly facing surface extending between the base and the top,
the fourth outwardly facing surface providing a fourth guiding
surface for making the posterior chamfer cut on the femur; wherein
one size cutting block can be used for femoral resection suitable
for any size femoral prosthesis.
41. The cutting block of claim 40, further comprising: at least two
holes extending from the top to the base.
42. The cutting block of claim 41, further comprising: a first slot
and a second slot, the first and the second slot extending through
the thickness of the cutting block and being parallel to each
other; and a third slot and a fourth slot, the third and the fourth
slot extending through the thickness of the block and being
parallel to each other and orthogonal to the first and the second
slot.
43. The cutting block of claim 41, further comprising: at least one
mounting means for mounting a tracker.
44. The cutting block of claim 43, wherein the mounting means is an
opening on one of the first, second, third or fourth outwardly
facing surface.
45. The cutting block of claim 44, further comprising: a tracker
mounted in the mounting means.
46. A method of resecting a femur, the method comprising the steps
of: locating a cutting block on the anterior surface of the femur
using a navigation system; making a distal cut on the femur using a
surface of the cutting block to guide the cutting instrument, the
cutting block being located on the anterior surface of the femur,
and the cut resulting in a planer distal surface; locating the
cutting block in a first location on the planer distal surface
using the navigation system; anchoring the cutting block on the
planer distal surface using pins; re-locating the cutting block in
a second, third and fourth position on the planer distal surface
using the navigation system; making an anterior cut, a posterior
cut, an anterior chamfer cut and a posterior chamfer cut using a
surface of the cutting block as a guide, the cutting block being
anchored in the first, second, third and fourth position
respectively during the making of the anterior cut, the posterior
cut, the anterior chamfer cut and the posterior chamfer cut.
47. The method of claim 46, further comprising the steps of: using
the pins installed for anchoring in the first position to
mechanically fix the rotation of the relocated cutting block in the
second, third, and fourth position.
48. A method of resecting a femur, the method comprising the steps
of: providing a cutting block adapted to resecting the femur for
installation of any size prosthetic device, the cutting block
having an angled surface, the angle of the angled surface matching
an angle on the prosthetic device; locating a cutting block on the
anterior surface of the femur using a navigation system; making a
distal cut on the femur using a surface of the cutting block to
guide the cutting instrument, the cutting block being located on
the anterior surface of the femur, and the cut resulting in a
planer distal surface; locating the cutting block in a first
location on the planer distal surface using the navigation system;
anchoring the cutting block on the planer distal surface using
pins; re-locating the cutting block in a second, third and fourth
position on the planer distal surface using the navigation system;
making an anterior cut, a posterior cut, an anterior chamfer cut
and a posterior chamfer cut using a surface of the cutting block as
a guide, the cutting block being anchored in the first, second,
third and fourth position respectively during the making of the
anterior cut, the posterior cut, the anterior chamfer cut and the
posterior chamfer cut.
49. The method of claim 48, further comprising the steps of: using
the pins installed for anchoring in the first position to
mechanically fix the rotation of the relocated cutting block in the
second, third, and fourth position.
50. A method of resecting bone, the method comprising the steps of:
providing a cutting block adapted to resecting the bone for
installation of any size prosthetic device; locating a cutting
block on the bone using a navigation system; making a cut on the
bone using a surface of the cutting block to guide the cutting
instrument; locating the cutting block in a first location on the
resected surface using the navigation system; anchoring the cutting
block on the resected surface using pins; using the pins installed
for anchoring in the first position to mechanically fix the
rotation of the relocated cutting block in subsequent positions for
resecting the bone.
Description
BACKGROUND OF THE INVENTION
[0001] This invention relates to method and apparatus for resecting
a bone. In particular this invention relates to a method and
apparatus for performing all of the bone resections required for
implanting a prosthesis using one bone resection instrument such as
a cutting block. More particularly, this invention relates to a
navigated cutting block that can be "floated" around the bone to be
resected to set up the planes for resection.
[0002] There are several types of prostheses known in the art. One
type is sometimes referred to as a "resurfacing type". In these
prostheses, the articular surfaces of the bones are "resurfaced"
with articular bearing components. One important aspect of these
procedures is the correct resection of the bones. These resections
must provide planes which are correctly angled in order to properly
accept the prosthetic components.
[0003] Recently, various computerized navigation systems have been
introduced to aid the practitioner during different surgical
procedures. These systems include multiple video cameras which are
deployed above the surgical site and a plurality of dynamic
reference frame (DRF) devices, also known as trackers, which are
attached to body parts and surgical instruments. The trackers can
be LED devices or reflective spheres which are visible to the
cameras. These trackers are attached to body parts and the surgical
instruments and preferably include light emitting devices, such as
light emitting diodes which are visible to the video cameras. The
trackers communicate position information to a camera system
located in the operating room. The camera system is connected to a
computer which tracks the location of the tracker and the patient
and displays the relationship on a CRT. Using software designed for
a particular surgical procedure, a computer receiving input from
the cameras guides the placement of surgical instruments such as
cutting blocks for bone resection.
[0004] The prior art cutting blocks have several shortcomings. In
case of a total knee arthroplasty that involves the replacement of
portions of the patella, femur and tibia with artificial
components, separate distal resection block and a block for making
remaining resections on the femur are required. Also, different
size resection blocks are required for different size implants.
This increases the inventory of parts in the operating room.
Additionally the prior art cutting blocks are sized in proportion
to the size of the implant and are not very suitable for minimally
invasive surgery. Therefore, there is a need for a navigable
cutting block that is small in size, suitable for use with all
sizes of implants and allows for all the necessary resections using
a single cutting block.
[0005] As used herein, when referring to bones or other parts of
the body, the term "proximal" means closer to the heart and the
term "distal" means more distant from the heart. The term
"inferior" means toward the feet and the term "superior" means
towards the head. The term "anterior" means towards the front part
of the body or the face and the term "posterior" means towards the
back of the body. The term "medial" means toward the midline of the
body and the term "lateral" means away from the midline of the
body.
SUMMARY OF THE INVENTION
[0006] Cutting blocks of the present invention overcome the
shortcomings of the prior art and provide a single cutting block
that can make all the resections on a bone (e.g., a femur), is
small in size and is suitable for use with all sizes of the
implants.
[0007] A first embodiment of the cutting block of the present
invention has a base, and a top connected to the base via four
walls. Each wall (i.e., the cutting guide) has an outwardly facing
surface to guide a cutting tool. Each wall also has an attachment
hole where a tracker may be attached. The cutting block is floated,
on the bone, free hand by the surgeon using the navigation system
to position it at correct locations for the bone resection. After
correctly locating the cutting block for each required cut, the
cutting block is fixed to the bone using pins and the bone
resected.
[0008] A second embodiment of the cutting block has a base, and a
top connected to the base via four walls. Three of the four walls
have outwardly facing surfaces that are used to guide a cutting
tool. Each one of these outwardly facing surface has an attachment
hole where a tracker may be attached. The cutting block is floated
free hand by the surgeon on the bone using the navigation system to
position it at correct locations for the bone resection. After
correctly locating the cutting block for each required cut, the
cutting block is fixed to the bone by inserting pins through the
holes in the cutting block and in the bone. Next, the bone is
resected. In this embodiment only three outwardly facing surfaces
are used to guide a cutting tool, however, the surfaces may be used
to guide the cutting tool in making more than one cuts on the
bone.
[0009] In yet another embodiment, the cutting block has two pairs
of slots in addition to features of the second embodiment. Once the
block is first attached to the distal end of the femur, the pins
that attached the block to the distal end are left in place and the
block relocated to make additional cuts on the bone by sliding the
pins in one of the two pairs of slots. Since the block is now
partially located by the pins, the rotation of the remaining
resection is mechanically set and need not be navigated. The second
set of slots is similarly used to make other resections.
[0010] In use the cutting blocks described above are floated on the
anterior surface of the bone to be resected, fixed in the correct
location and one of the outwardly facing surfaces used to make the
distal cut on the bone. Thereafter, the cutting block is floated on
the resected distal end of the bone and fixed in the correct
location for making another cut. The process is repeated to as many
times as necessary. In one embodiment the cutting blocks rotational
position is mechanically set as described previously.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is an isometric view of a cutting block.
[0012] FIG. 2 is an isometric view of the cutting block of FIG. 1
from a different angle.
[0013] FIG. 3 is a plan view of the cutting block of FIG. 1.
[0014] FIGS. 4, 5 and 6 are side views from different sides of the
cutting block of FIG. 1.
[0015] FIG. 7 is another plan view showing the base of the cutting
block of FIG. 1.
[0016] FIG. 8 is an isometric view of another embodiment of a
cutting block.
[0017] FIG. 9 is an isometric view of the cutting block of FIG. 8
from a different angle.
[0018] FIG. 10 is a plan view of the cutting block of FIG. 8.
[0019] FIGS. 11, 12 and 13 are side views from different sides of
the cutting block of FIG. 8.
[0020] FIG. 14 is another plan view showing the base of the cutting
block of FIG. 8.
[0021] FIG. 15 is an isometric view of another embodiment of a
cutting block.
[0022] FIG. 16 is an isometric view of the cutting block of FIG. 14
from a different angle.
[0023] FIG. 17 is a plan view of the cutting block of FIG. 14.
[0024] FIGS. 18, 19 and 20 are side views from different sides of
the cutting block of FIG. 14.
[0025] FIG. 21 is another plan view showing the base of the cutting
block of FIG. 14.
[0026] FIG. 22A shows cutting block and tracker placed on a femur
for making a distal cut.
[0027] FIG. 22B shows cutting block and tracker placed on a femur
for making an anterior cut.
[0028] FIG. 22C shows cutting block and tracker placed on a femur
for making a posterior cut.
[0029] FIG. 22D shows cutting block and tracker placed on a femur
for making an anterior chamfer cut.
[0030] FIG. 22E shows cutting block and tracker placed on a femur
for making a posterior chamfer cut.
DETAILED DESCRIPTION
[0031] FIGS. 1-7 show a first embodiment of a cutting block 20.
Cutting block 20 has a base 22 and a top 24. Base 22 is connected
to top 24 via four walls 26, 28, 30 and 32. Wall 28 runs from base
22 to top 24 and has an outwardly facing surface 29 to guide a
cutting tool. Surface 29 of wall 28 may be angled to match an angle
on prosthesis such as a femoral prosthesis. The angle may be, for
example, seven degrees with respect to base 22. The outwardly
facing surface 29 may be used to make, for example, an anterior cut
on a femur. Wall 26 runs from base 22 to top 24 and has an
outwardly facing surface 27 to guide a cutting tool. Outwardly
facing surface 27 of wall 26 may be used, for example, to make
distal and posterior cuts on a femur. Wall 30 runs from base 22 to
top 24 and has yet another outwardly facing surface 31 that may
guide a cutting tool. Wall 30 may be angled with respect to base
22. The angle that wall 30 forms with base 22 may be determined
based upon the angle at which certain cut, for example, a chamfer
cut on a femur is to be made. Wall 32 runs from base 22 to top 24
and has yet another outwardly facing surface 33 that may guide a
cutting tool. Wall 32 may also be angled with respect to base 22.
The angle that wall 32 forms with base 22 may also be determined
based upon the angle that a certain cut, for example, a chamfer cut
on a femur is to be made. The angles made by walls 30 and 32 with
base 22 may be same or may differ from each other. Cutting block 20
may be formed, for example, from a solid or hollow piece of metal,
plastic or other suitable material and provide the outwardly facing
surfaces described above and other features that will be described
hereafter.
[0032] Walls 26, 28, 30, 32 have attachment holes 34, 36, 38 and 40
respectively. A tracker may be attached to any one of the
attachment holes 34, 36, 38 and 40, for navigating cutting block 20
for proper positioning on the corresponding surface on the bone.
Holes 34, 36, 38 and 40 each have small openings 42 and 44 seen in
FIGS. 1 and 3. Openings 42 and 44 accommodate spring loaded ball
like structures on the tracker attached in any one of the holes 34,
36, 38 and 40, thereby aiding in attachment of tracker to cutting
block 20. Top 24 has four holes 46, 48, 50 and 52. A pin may be
driven through one or more of holes 46, 48, 50 and 52 to attach
cutting block 20 to a bone. Top 24 may have more or less than four
holes.
[0033] FIGS. 8-14 show a cutting block 54 that is a second
embodiment of the invention. If the chamfer cuts on a bone are to
be at same angle, cutting block 20 can be made smaller. Cutting
block 54 is an example of such smaller block that is more suitable
for minimally invasive surgery. Cutting block 54 has a base 56 and
a top 58. Walls 60, 62, 64 and 66 run from base 56 to top 58. Wall
62 has an outwardly facing surface 63 which may guide a cutting
tool. Wall 62 may be angled, for example, seven degrees with
respect to the base, to match the angle on the prosthesis to be
used. Wall 64 has an outwardly facing surface 65 to guide a cutting
tool. Wall 64 is angled with respect to the base. The angle is
determined based upon the angle that a certain cut, for example, a
chamfer cut on a femur is to be made. Outwardly facing surface 65
may also be used to make another cut, for example, a second chamfer
cut that is at the same angle as the first chamfer cut. Wall 60 has
an outwardly facing surface 61 to guide a cutting tool. Outwardly
facing surface 61 may be used, for example, to make distal and
posterior cuts on a femur.
[0034] Walls 60, 62 and 64 have attachment holes 68, 70 and 72
respectively. A tracker may be attached to any one of the
attachment holes 68, 70 and 72. Attachment means of another shape
or design, for example, an opening of non-circular shape or a
projection or a mechanical detail of suitable geometry and
construction may also be used for attaching a tracker. Holes 68, 70
and 72 each have small openings 74, 76 as seen in FIGS. 8 and 10.
Openings 74 and 76 accommodate spring loaded ball like structures
on the tracker attached in holes 68, 70, and 72, thereby aiding in
attachment of the tracker to cutting block 54. Top 58 of cutting
block 54 has two holes 75 and 77. Top 58 may have more or less
holes. A pin may be driven through one or more holes 75 and 77 to
attach cutting block 54 to a bone.
[0035] FIGS. 15-21 show yet another embodiment of the present
invention--cutting block 78. Cutting block 78 has a base 80 and a
top 82. Walls 84, 86 and 88 extend from base 80 to top 82. Wall 84
has an outwardly facing surface 85 that can guide a cutting tool.
The outwardly facing surface 85 may be used, for example, to make
the distal and the posterior cut on a femur. Wall 86 has an
outwardly facing surface 87 that can guide a cutting tool for
making, for example, an anterior cut on a femur. The outwardly
facing surface 87 of wall 86 may be at an angle, for example, seven
degrees with respect to base 80. This angle may match the
corresponding angle on the prosthesis to be used. Wall 88 has an
outwardly facing surface 89 that can guide cutting tools for
making, for example, chamfer cuts on a femur. The outwardly facing
surface 89 forms an angle with base 80. This angle may correspond
with the angle of the chamfer cut on a femur.
[0036] Walls 84, 86 and 88 have attachment holes 90, 92 and 94.
Each attachment hole 90, 92, or 94 has small openings 96 and 98.
The attachment of a tracker 112 to cutting block 78 is similar to
the attachment of tracker to cutting block 54 and was described in
detail previously in context of cutting block 54. Cutting block 78
has two holes 100 and 102. A pin 114 may be driven through one or
both of holes 100 and 102 to attach cutting block 78 to a bone.
Cutting block 78 has two parallel slots 104 and 106 that run in
directions generally orthogonal to the outwardly facing surface 87.
Cutting block 78 has a second pair of parallel slots 108 and 110
that run in direction generally orthogonal to slots 104 and
106.
[0037] FIGS. 22A-22E show cutting block 78 with tracker 112
attached to it via attachment holes 90, 92 or 94. Tracker 112 is
used to position cutting block 78 on different surfaces of a femur
for making various cuts. However, tracker 112 can be attached to
cutting block 78 via alternate means. The alternate methods may not
permit obtaining accurate positional information on all 6
degrees-of-freedom, but there may be times during a surgical
procedure where 6 degree-of-freedom positional information is not
required. Some instruments have recesses intended for a purpose
other than attachment of a tracker; however, these recesses can
also be used to locate a tracker. For example, a slotted cutting
block with a recess intended to guide a saw blade can be used to
locate a tracker relative to the cutting block through the use of
an adaptor that has both a feature approximately the same thickness
as the saw blade and that can fit in the recess and a feature that
can be utilized to attach the tracker to the adaptor. Some
instruments have surfaces intended for a purpose other than tracker
attachment; however, these surfaces can also be used to locate a
tracker. For example, an open-face cutting block, such as cutting
block 78, with a surface intended to guide a saw blade can be used
to locate a tracker, such as tracker 112, relative to the cutting
block through the use of an adaptor (not shown) that has both a
feature that can be placed in direct apposition to the surface and
a feature that can be utilized to attach the tracker to the
adaptor.
[0038] In use, for example, in a surgery to implant a
tricompartmental (i.e., a component for replacing the medial and
lateral condyler and the patellar groove on either the left or
right femur) femoral component on the distal femur, cutting block
20, 54 or 78 is located on the anterior surface of a femur using
navigation. To this end, the tracker pins are inserted into the
bone and anatomical landmarks digitized. Tracker 112 is attached to
hole 34, 68 or 90 and block 20, 54 or 78 is floated (i.e., placed
free hand) onto the femur in correct orientation. In this position
the outwardly facing surface 27, 61 or 85 is in correct position to
resect the distal condyler surface of the femur. At this time block
20, 54 or 78 is pinned down on the femur by driving pins through a
pair of holes on top 24, 58 or 82 respectively. Holes 46, 52 (or
48, 50) may be used when cutting block 20 is being used. Holes 75
and 77 are used when cutting block 54 is employed. And, in case
cutting block 78 is being used, pins may be driven through holes
100 and 102. Once cutting block 20, 54 or 82 is pinned into place,
the distal condyle is resected using outwardly facing surfaces 27,
61 or 85 respectively.
[0039] After distal resection, cutting block 20 is rotated and
placed on the distal resected end of the femur so that base 22
rests on the resected distal surface. Cutting block 20 is placed
free hand onto the femur in correct orientation. In this
orientation the anterior cutting surface (i.e., the outwardly
facing surface 29) is in the appropriate anterior-posterior
location and the internal/external rotation of the block matches
that of the transepicondylar axis, anterior-posterior axis or the
orientation the surgeon sets using the navigation system. Now
cutting block 20 is pinned into place by driving pins through at
least two of four the holes 46, 48, 50 and 52. Next anterior
resection is performed using the outwardly facing surface 29 as a
guide for a cutting tool. Next, cutting block 20 is removed from
the bone and tracker attached in hole 34. Cutting block 20 is
placed in the correct orientation for the posterior cut, pinned to
the distal end as previously described, tracker removed, and
posterior cut made using the outwardly facing surface 27 as a guide
for the cutting tool. Next, cutting block 20 is removed from bone,
a tracker attached to hole 40, cutting block 20 is placed in the
correct orientation for a chamfer cut and pinned to the bone as
previously described, tracker removed and a chamfer cut made using
outwardly facing surface 33. A second chamfer cut may be made in a
manner similar to the first chamfer cut described above. For second
chamfer cut the surgeon may be able to choose between outwardly
lying surface 31 or 33 if the prosthesis has two identical chamfer
angles. If the prosthesis has differing chamfer angles, one cut may
be made using each one of surfaces 31 and 33.
[0040] When cutting block 78 is used, the procedure for making the
distal cut and the anterior cut is same as described in the context
of cutting block 20. In case of cutting block 78 holes 100 and 102
are used to pin the block to the bone for making the distal and the
anterior cuts using outwardly facing surfaces 85 and 87
respectively. Thereafter, the block is removed from the bone but
the pins 116 and 118 are left in place for the anterior resection.
Since pins 116 and 118 are used to position cutting block 78 for
the remaining resection, the rotation of the remaining resections
is mechanically set and need not be navigated. Next, pins 116 and
118 are inserted in slots 104 and 106 and the cutting block 78 is
slid along the pins to correct location for making the posterior
cut. A tracker may be attached to hole 90 to navigate the block for
posterior cut. Once correctly located, cutting block 78 is pinned
in place by driving at least one pin 114 through one of the holes
100 and 102. Now the posterior resection is performed using the
outwardly facing surface 87 as a guide for the cutting tool.
[0041] Next, cutting block 78 is removed, leaving pins 116 and 118
that were engaged in slots 104 and 106 in place. Cutting block 78
is rotated and pins 116 and 118 that were left in the place are
inserted in slots 108 and 110. Cutting block 78 is slid along pins
116 and 118 to correct location for making a chamfer cut. A tracker
may be attached to hole 94 to navigate the block for chamfer cut.
Once correctly located, cutting block 78 is pinned in place by
driving at least one pin 114 though holes 100 and 102. Now the
anterior or posterior chamfer cut is made. Next, the process is
repeated with the block rotated by 180 degrees to make the second
chamfer cut.
[0042] When cutting block 54 is used, the procedure for making the
distal cut and the anterior cut is same as described in the context
of cutting block 20. In case of cutting block 54, holes 75 and 77
are used to pin block 54 to the bone. The distal and anterior cuts
are made using the outwardly facing surfaces 61 and 63
respectively. Thereafter, the cutting block 78 is removed from the
distal surface, the tracker attached to hole 68, the cutting block
78 floated into correct orientation and position for making the
posterior cut, pinned in place by driving pins through holes 75 and
77 and the posterior cut made using the outwardly facing surface
61.
[0043] Next, cutting block 54 is removed from the bone, a tracker
attached to hole 72 and cutting block 54 floated in correct
orientation and position for making a chamfer cut. Cutting block 54
is pinned to the bone as described previously and the chamfer cut
is made using the outwardly facing surface 65. Next the cutting
block 54 is removed from the bone, tracker reattached to hole 72
and the process repeated with cutting block 54 rotated 180 degrees.
Cutting block 54 is floated in correct orientation and position for
making a second chamfer cut, it is pinned to the bone and chamfer
cut is made using the outwardly facing surface 65.
[0044] Cutting block 20, 54 or 78 may also be used, for example,
for resection of tibia and talus to install ankle prosthesis. The
ankle may be approached from the lateral side, the fibula moved to
allow access to the ankle joint and the prosthesis installed after
bone resection. Cutting block 20, 54, or 78 may floated on the
talus and three cuts--a distal cut and two chamfer cuts can be
made. In contrast to the traditional cutting block that require
different sizes, the same cutting block 20, 54 or 78 can be used
for any size bone (such as a talus or a femur) since the cutting
surfaces are referenced to each other in terms of angular
relationship but not linear relationship which is set by the
navigation system.
[0045] Although the invention herein has been described with
reference to particular embodiments, it is to be understood that
these embodiments are merely illustrative of the principles and
applications of the present invention. It is therefore to be
understood that numerous modifications may be made to the
illustrative embodiments and that other arrangements may be devised
without departing from the spirit and scope of the present
invention as defined by the appended claims.
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