U.S. patent application number 10/357282 was filed with the patent office on 2004-08-05 for apparatus for knee surgery and method of use.
Invention is credited to Coon, Thomas M., Farling, Toby N., Gareiss, Warren Scott, Goble, E. Marlowe, Hodorek, Robert A., Justin, Daniel F., Smucker, Donald M., Tria, Alfred J. JR., Van Zile, Richard R..
Application Number | 20040153066 10/357282 |
Document ID | / |
Family ID | 32770988 |
Filed Date | 2004-08-05 |
United States Patent
Application |
20040153066 |
Kind Code |
A1 |
Coon, Thomas M. ; et
al. |
August 5, 2004 |
Apparatus for knee surgery and method of use
Abstract
The present invention comprises a set of instruments and a
method for their use in preparing a knee joint to receive knee
implants. The inventive instruments and method are generally
suitable for knee joint surgery. Furthermore, they include features
that make them suitable for performing a minimally invasive knee
surgery in which a smaller than normal incision is made and
oriented to preserve the quadriceps mechanism and protect the
suprapatellar pouch. The instruments permit switching from a
minimally invasive technique to a standard open technique at any
point in the procedure. An illustrative set of instruments for
total knee arthroplasty and an associated minimally invasive
technique are described.
Inventors: |
Coon, Thomas M.; (Redding,
CA) ; Goble, E. Marlowe; (Alta, WY) ; Tria,
Alfred J. JR.; (Princeton, NJ) ; Gareiss, Warren
Scott; (Columbia City, IN) ; Hodorek, Robert A.;
(Warsaw, IN) ; Farling, Toby N.; (Warsaw, IN)
; Justin, Daniel F.; (Logan, UT) ; Smucker, Donald
M.; (Perrysburg, OH) ; Van Zile, Richard R.;
(Bryan, OH) |
Correspondence
Address: |
CARY R. REEVES
P.O. BOX 1268
ALEDO
TX
76008
US
|
Family ID: |
32770988 |
Appl. No.: |
10/357282 |
Filed: |
February 3, 2003 |
Current U.S.
Class: |
606/54 |
Current CPC
Class: |
A61B 17/1735 20130101;
A61B 17/155 20130101; A61B 17/1764 20130101; A61B 17/1675 20130101;
A61B 17/00234 20130101; A61F 2/4657 20130101; A61B 2090/062
20160201; A61B 17/157 20130101; A61B 17/158 20130101; A61B 17/1767
20130101; A61F 2/4684 20130101 |
Class at
Publication: |
606/054 |
International
Class: |
A61F 004/00 |
Claims
What is claimed is:
1. A patella resection guide for guiding a cutter to cut a patella
having an anterior side, an opposite posterior side, a medial side
and a lateral side, the patella resection guide comprising: a first
jaw for engaging said medial side of said patella; a second jaw for
engaging said lateral side of said patella; means for moving the
first jaw relative to the second jaw from a first position in which
the jaws are disengaged from said medial and lateral sides of said
patella to a second position in which the jaws are engaged with
said medial and lateral sides of said patella, the means being
actuable from a location that is medial or lateral of said patella;
and means for guiding a cutter to cut said patella.
2. The patella resection guide of claim 1 further comprising means
for gauging the amount of bone to be resected.
3. The patella resection guide of claim 1 further comprising means
for gauging the amount of bone that will remain after the patella
is cut.
4. A patella resection guide for guiding a cutter to cut a patella
having an anterior side, an opposite posterior side, a medial side
and a lateral side, the patella resection guide comprising: a first
jaw shaped to engage said medial side of said patella; a second jaw
shaped to engage said lateral side of said patella; a handle
connecting the first and second jaws in translating relationship,
the handle being actuable to move the jaws from a first position in
which the jaws are disengaged from said medial and lateral sides of
said patella to a second position in which the jaws are engaged
with said medial and lateral sides of said patella, the handle
being actuable from a location that is medial or lateral of said
patella.
5. The patella resection guide of claim 4 wherein the jaws are have
curved faces for engaging curved sides of said patella.
6. The patella resection guide of claim 4 wherein the handle
comprises a guide arm connecting the first and second jaws, at
least one of the first and second jaws mounted for translation
along the guide arm to move from the first position to the second
position.
7. The patella resection guide of claim 6 wherein the jaws remain
parallel as they are moved from the first to second positions.
8. The patella resection guide of claim 7 wherein the handle
comprises an actuator pivotably mounted on the handle at a first
end and connected to one of said first and second jaws at a second
end such that pivoting the actuator moves the jaws between the
first and second positions.
9. The patella resection guide of claim 6 wherein the handle
further comprises a first grip portion connected to the first jaw
and a second grip portion connected to the second jaw, the first
and second grip portions being parallel to one another, such that
pressing the first and second grip portions together in parallel
manner causes at least one of the first and second jaws to
translate along the guide arm from the first position to the second
position.
10. The patella resection guide of claim 4 further comprising a
depth gauge removably mountable on the first side of the resection
guide to indicate the amount of bone to be removed from said
patella and alternately mountable on the second side of the
resection guide to indicate the amount of bone to remain on said
patella.
11. The patella resection guide of claim 4 further comprising a
cutter guide to guide a cutter.
12. The patella resection guide of claim 11 wherein the cutter is
selected from the list consisting of a saw blade, a side cutting
reamer, a end cutting reamer, and a water jet cutter.
13. A patella resection guide comprising: a first side; a second
side; and a depth gauge removably mountable on the first side of
the resection guide to indicate the amount of bone to be removed
from said patella and alternately mountable on the second side of
the resection guide to indicate the amount of bone to remain on
said patella.
14. A patella resection guide for guiding a cutter to cut a patella
having an anterior side, an opposite posterior side, and a
periphery around the patella, the patella resection guide
comprising: a first jaw member shaped to engage said periphery of
said patella; a second jaw member shaped to engage said periphery
of said patella, the second jaw member connected to the first jaw
member in translating relation; a first handle connected to the
first jaw member; a second handle connected to the second jaw
member, the second handle being actuable to move the second jaw
member in a motion plane toward and away from the first handle; and
a cutter guide adjacent the jaws, the cutter guide able to guide a
cutter to cut in a plane parallel to the jaw motion plane.
15. A patella resection guide for guiding a cutter to cut a patella
having an anterior side, an opposite posterior side, and a
periphery around the patella, the patella resection guide
comprising: a first jaw member shaped to grip said periphery of
said patella; a second jaw member shaped to grip said periphery of
said patella; a support member connecting the first jaw member in
translating relationship to the second jaw member, the support
constraining the jaw members to remain parallel when they move
relative to one another; a handle actuable to move the first and
second jaw members in a motion plane from a first position in which
the jaw members are further from one another to a second position
in which the jaw members are nearer one another; a cutter guide
adjacent the jaws, the cutter guide able to guide a cutter to cut
in a plane parallel to the jaw motion plane.
16. A method comprising the steps of: providing a patella resection
guide having patella gripping jaws and a cutter guide; making an
incision on at least one of the medial and lateral sides of a knee
to expose said patella from the side; gripping the medial and
lateral sides of the patella with the jaws of the patella resection
guide while the patella remains in its normal orientation relative
to the femur; and guiding a cutter with the cutter guide through
the incision from the side of the knee to resect the patella.
17. The method of claim 16 further comprising the steps of:
providing a gauge alternately connectable to a first side of the
patella resection guide to indicate the amount of bone to be
removed and to a second side of the patella resection guide to
indicate the amount of bone to remain; determining whether to gauge
the amount of bone to remove or the amount of bone to remain;
attaching the depth gauge to the appropriate side; and cutting the
bone.
18. A femoral distal cut guide for cutting a femur, the femur
having a frontal plane, a sagittal plane, a femoral head adjacent a
hip joint, a femoral shaft with an intramedullary canal, a condylar
portion adjacent a knee joint having a medial side and a lateral
side, an anatomic axis lying along the intramedullary canal, and a
mechanical axis lying along a line from the center of the femoral
head to the center of the knee joint, the cut guide comprising: an
intramedullary rod having a longitudinal rod axis; and a distal cut
guide, the distal cut guide mounted on the intramedullary rod at an
angle to the longitudinal rod axis, as measured in the frontal
plane, so that aligning the intramedullary rod with the anatomic
axis and extending the distal cut guide toward the side of the knee
orients the distal cut guide to guide a cutter from the side of the
knee to cut the distal femur perpendicular to the mechanical
axis.
19. The femoral distal cut guide of claim 18 further comprising an
intramedullary alignment guide connected to the intramedullary rod
and having a longitudinal guide axis at an angle to the
longitudinal rod axis, as measured in the frontal plane, so that
when the rod is aligned with the anatomic axis and the longitudinal
guide axis is parallel to the frontal plane, the longitudinal guide
axis is perpendicular to the femoral mechanical axis and extended
toward one of the medial and lateral sides of the knee.
20. The femoral distal cut guide of claim 19 further comprising a
distal cut guide mounted for motion parallel to the longitudinal
guide axis with the distal cut guide directed toward one of the
medial and lateral sides of the knee, the distal cut guide able to
be translated along the longitudinal guide axis to a position
adjacent one of the medial and lateral sides of the knee.
21. The femoral distal cut guide of claim 20 wherein the
intramedullary alignment guide further includes a reference surface
for contacting a distal femoral condyle to position the distal cut
guide to make a cut at a predetermined distance from the femoral
condyle.
22. The femoral distal cut guide of claim 20 wherein the
intramedullary alignment guide further includes a reference surface
for contacting said intercondylar sulcus to position the distal cut
guide to make a cut at a predetermined distance from the
intercondylar sulcus.
23. A method of cutting a distal femur comprising the steps of:
providing a distal cut guide having an intramedullary rod; making
an incision on at least one of the medial and lateral sides of a
knee to expose the distal femur from the side; inserting the
intramedullary rod into an intramedullary canal of the femur;
orienting the distal cut guide so that it extends toward one of the
medial and lateral sides of the femur; and guiding a cutter with
the cutter guide to cut the distal femur from the side to form a
planar distal surface.
24. The method of claim 23 further comprising the steps of:
providing an alignment guide extending at an angle to the
intramedullary rod; providing a distal cut guide having a cutter
guide and being mounted for translation along the alignment guide;
and sliding the distal cut guide along the alignment guide until
the distal cut guide is adjacent the side of the femur.
25. The method of claim 24 further comprising the steps of:
positioning the alignment guide so that a reference surface on the
alignment guide contacts a distal femoral condyle; and guiding a
cutter with the distal cut guide to make a cut at a predetermined
distance from the femoral condyle.
26. The method of claim 24 further comprising the steps of:
positioning the alignment guide so that a reference surface on the
alignment guide contacts the intramedullary sulcus; and guiding a
cutter with the distal cut guide to make a cut at a predetermined
distance from the intramedullary sulcus.
27. A tibial cut guide assembly comprising: a support having a
longitudinal support axis; a cross member mounted on the support,
the cross member having a cross member axis perpendicular to the
support axis, the cross member axis and support axis defining a
guide plane, the cross member having a slope reference oriented at
a predetermined slope angle relative to the guide plane; a cut
guide having a cross member engaging end and a cutter guide, the
cross member engaging end being mounted on the cross member in
engagement with the slope reference, the cutter guide defining a
cut plane that is oriented at a predetermined slope angle relative
to the guide plane as determined by the slope reference.
28. The tibial cut guide assembly of claim 27 further comprising a
plurality of interchangeable cross members, each interchangeable
cross member having a slope reference oriented at a different
predetermined slope angle relative to the guide plane.
29. The tibial cut guide assembly of claim 27 wherein the cut guide
is mounted on an arm projecting upwardly and inwardly from the
cross member to position the cutter guide adjacent a tibia to be
cut.
30. The tibial cut guide assembly of claim 27 wherein the cut guide
is translatable along the cross member from a first position to a
second position, the cutter guide defining parallel planes in the
first and second position.
31. The tibial cut guide assembly of claim 30 wherein the cross
member is translatable up and down along the support axis.
32. The tibial cut guide assembly of claim 27 further comprising a
proximal adjustment mechanism actuable to change the spacing of a
proximal end of the support and a proximal end of a tibia to change
the angle of the support axis relative to a tibial axis.
33. The tibial cut guide assembly of claim 32 wherein the proximal
adjustment mechanism comprises a screw threadingly engaging the
support and abuttable with a proximal end of a tibia.
34. A tibial cut guide assembly for cutting a proximal end of a
tibia having a proximal end, a distal end, a tibial shaft, a tibial
axis along the shaft, an anterior side parallel to a frontal plane,
a medial side parallel to a sagittal plane, and a lateral side
parallel to said sagittal plane, the tibial cut guide assembly
comprising: a support having a support axis, the support being
mountable on said tibia with the support axis parallel to said
tibial axis; a cut guide, the cut guide being mounted on the
support with the cut guide oriented to guide a cutter obliquely
toward said tibia between the anterior side and one of the medial
and lateral sides of said tibia to cut the proximal end of said
tibia when the support is mounted on said tibia.
35. The tibial cut guide assembly of claim 34 further comprising a
cross member mounted on the support connecting the support and cut
guide, the cross member having a cross member axis perpendicular to
the support axis, the cross member axis and support axis defining a
guide plane, the guide plane being positionable parallel to the
frontal plane and the tibial axis, the cross member having a slope
reference oriented at a predetermined slope angle relative to the
guide plane.
36. The tibial cut guide assembly of claim 35 wherein the cut guide
has a cross member engaging end and a cutter guide, the cross
member engaging end being mounted on the cross member in engagement
with the slope reference, the cutter guide defining a cut plane
that is oriented at a predetermined slope angle relative to the
guide plane as determined by the slope reference, the cutter guide
being translatable along the cross member from a first position to
a second position, the cutter guide defining parallel planes in the
first and second position.
37. A tibial cut guide assembly comprising: an alignment bar having
a longitudinal alignment bar axis; a boom mounted on the alignment
bar, the boom having a boom axis perpendicular to the alignment bar
axis, the boom axis and alignment bar axis defining a guide plane,
the boom having a slope reference oriented at a predetermined slope
angle relative to the guide plane; a cut guide having a boom
engaging end and a cutter guide, the boom engaging end being
mounted on the boom in engagement with the boom slope reference,
the cutter guide defining a cut plane that is oriented at a
predetermined slope angle relative to the guide plane as determined
by the boom slope reference.
38. The tibial cut guide assembly of claim 37 wherein the cut guide
slidingly engages the boom so that the cut guide can slide along
the boom from a first position further from the alignment bar to a
second position nearer to the alignment bar while maintaining the
cut plane at a constant angle to the guide plane.
39. The tibial cut guide assembly of claim 38 wherein the boom is
mounted for translation along the alignment bar axis so that moving
the boom along the alignment bar axis changes the level of the cut
plane.
40. The tibial cut guide assembly of claim 37 further including a
depth gauge, the depth gauge including a blade having a reference
end, the depth gauge being mounted on the assembly with the
reference end a predetermined fixed distance from the cut plane as
measured along the alignment bar axis.
41. The tibial cut guide assembly of claim 37 wherein the cutter
guide comprises a saw blade slot defining a plane for a saw
blade.
42. A method for cutting a proximal end of a tibia having a
proximal end, a distal end, a tibial shaft, a tibial axis along the
shaft, an anterior side parallel to a frontal plane, a medial side
parallel to a sagittal plane, and a lateral side parallel to said
sagittal plane, the method comprising the steps of: mounting a cut
guide on the tibia with the cut guide oriented to guide a cutter
obliquely toward the tibia between the anterior side and one of the
medial and lateral sides of the tibia; and guiding a cutter
obliquely toward the tibia with the cut guide to cut the proximal
end of the tibia.
43. The method of claim 42 further comprising the steps of:
providing a support having a support axis; mounting the support on
said tibia with the support axis parallel to the tibial axis;
mounting the cut guide on the support.
44. The method of claim 43 wherein the step of mounting the support
includes mounting the support on the anterior surface of the
tibia.
45. The method of claim 44 further comprising the step of adjusting
the cut guide mediolaterally while maintaining parallel cut
planes.
46. A method for cutting a proximal end of a tibia having a
proximal end, a distal end, a tibial shaft, a tibial axis along the
shaft, an anterior side parallel to a frontal plane, a medial side
parallel to a sagittal plane, and a lateral side parallel to said
sagittal plane, the method comprising the steps of: providing a
tibial alignment bar having an alignment bar axis and a tibial boom
mounted on the alignment bar for translation along the alignment
bar axis, the tibial boom having a boom axis perpendicular to the
alignment bar axis, the alignment bar axis and boom axis together
defining a guide plane, the boom further including a posterior
slope reference defining a predetermined angle relative to the
guide plane; mounting the alignment bar on said tibia with the
alignment bar axis parallel to the tibial axis; providing a cut
guide; mounting the cut guide on the boom for translation along the
boom axis and in engagement with the posterior slop reference such
that the cut guide is oriented to guide a cutter obliquely toward
the tibia between the anterior side and one of the medial and
lateral sides of the tibia to cut a planar surface at the
predetermined angle relative to the guide plane; and guiding a
cutter obliquely toward the tibia with the cut guide to cut the
proximal end of the tibia.
47. The method of claim 46 further including the steps of:
providing a tibial alignment bar with a selection of booms having
different posterior slope reference angles; determining a desired
slope; picking a boom corresponding to the desired slope.
48. The method of claim 46 further comprising the step of making an
incision on the at least one of the medial and lateral sides of a
knee to expose the proximal tibia from the side.
49. The method of claim 48 further comprising the step of adjusting
the cut guide mediolaterally to be adjacent until it is obliquely
adjacent the proximal tibia.
50. The method of claim 49 further comprising the step of
positioning the tibial boom along the alignment bar axis to set the
depth of the tibial cut.
51. The method of claim 46 further comprising the steps of: setting
a proximal end of the tibial alignment bar adjacent the proximal
end of the tibia at a desired mediolateral position and the distal
end of the alignment bar adjacent the distal end of the tibia at a
desired mediolateral position to establish mediolateral vertical
reference axis relative to which the cut guide sets the
varus-valgus angle; independently of the mediolateral setting,
setting the proximal end of the alignment bar at a desired
anteroposterior position relative to the proximal end of the tibia
and the distal end of the alignment bar at a desired
anteroposterior position relative to the distal end of the tibia to
establish an anteriorposterior vertical reference axis relative to
which the cut guide sets the posterior slope; adjusting the cut
guide mediolaterally while maintaining parallel cut planes having
the same varus-valgus angle and posterior slope; adjusting the
proximal distal position of the cut plane independently of
mediolateral position to set the depth of cut; and guiding a cutter
with the cut guide to cut the tibia at the independently
established depth, varus-valgus angle, and posterior slope.
52. A guide for establishing a position reference on a distal
portion of a femur having a distal end, an anterior surface, a
medial side surface, a lateral side surface, posterior condyles,
and anatomic landmarks, the guide comprising: a base having a
reference surface for engaging said distal end; and a pin guide
mounted for rotation relative to the base, the pin guide including
at least one pin guide hole for guiding a reference pin to engage
one of said medial and lateral side surfaces of said distal
femur.
53. The guide of claim 52 wherein the pin guide has an alignment
portion for aligning with anatomic landmarks on said distal
femur.
54. The guide of claim 53 further comprising a foot connected to
the base, the foot extending at an angle from the reference surface
to engage said posterior condyles to establish a posterior size
reference.
55. The guide of claim 54 further comprising a plate, the plate
rotationally mounted to the base and the pin guide mounted on the
plate so that as the pin guide rotates relative to the base the pin
guide also rotates relative to the base.
56. The guide of claim 55 wherein the base includes a plurality of
rotational alignment holes and the plate includes a plurality of
alignment holes, different pairs of holes aligning at different
angles of rotation between the base and plate.
57. The guide of claim 56 wherein the pin guide is mounted for
translation relative to the plate so that the plate can be rotated
to set the rotation of the pin guide hole relative to the base and
the pin guide can be translated relative to the plate to set the
spacing of the pin guide hole from the base.
58. The guide of claim 57 further including an anterior probe
mounted for translation relative to the plate, the anterior probe
having a probe tip for engaging said femoral anterior surface, the
probe having size indicia to indicate the distance the probe is
translated relative to the plate.
59. The guide of claim 58 further including a feeler gauge that
indexes the translation of the pin guide relative to the plate to
the translation of the probe relative to the plate so that sizing
information determined by the probe is reflected in the position of
the pin guide.
60. The guide of claim 59 wherein the pin guide is mounted for
mediolateral translation relative to the plate so that it can be
moved to a position adjacent the side of the femur.
61. A guide for establishing a position reference on a distal
portion of a femur having a distal end, an anterior surface, a
posterior surface, a medial side surface, a lateral side surface,
posterior condyles, a femoral axis, and anatomic landmarks, the
guide comprising: means for establishing a desired rotation angle
relative to said femoral axis; and means for establishing a desired
A/P position between said anterior and posterior surfaces of said
femur; and means for establishing a datum on said distal femur that
records the rotation angle and A/P position in such a way that the
datum can be subsequently referenced by bone cutting guides to
produce bone cuts relative to the rotation and position
information.
62. The guide of claim 61 wherein the datum comprises an element
selected from the group consisting of a pin, a hole, a slot, and a
notch.
63. The guide of claim 61 wherein the datum is able to be
referenced by subsequent instruments to establish the varus-valgus
angle, external rotation, and anteroposterior position of bone
cuts.
64. The guide of claim 61 wherein the means for establishing a
desired rotation angle comprises a base having a reference surface
for engaging said distal end of said femur and a datum guide
mounted for rotation relative to the base, the datum guiding the
positioning of a datum on one of said medial and lateral side
surfaces of said distal femur.
65. A method for establishing a position reference datum on a
distal portion of a femur having an anterior surface, a posterior
surface, posterior condyles, a femoral axis, medial and lateral
epicondyles, and an A/P axis, the method comprising the steps of:
determining a desired rotation angle relative to the femoral axis;
determining a desired A/P position between the anterior and
posterior surfaces of the femur; creating a datum on the distal
femur that records the rotation angle and A/P position in such a
way that the datum can be subsequently referenced by bone cutting
guides to produce bone cuts relative to the rotation and position
information.
66. The method of claim 65 wherein the step of determining a
desired rotation angle is accomplished by aligning a datum guide
relative to an anatomic reference selected from the group
consisting of the femoral posterior condyles, a line drawn between
the medial and lateral femoral epicondyles, and a line drawn along
the distal femoral A/P axis.
67. The method of claim 65 wherein the step of determining a
desired A/P position comprises contacting the anterior femoral
surface with a probe.
68. The method of claim 65 wherein the step of creating a datum
comprises a step selected from the group consisting of drilling at
least one hole, cutting at least one slot, and setting at least one
pin in the femur.
69. The method of claim 65 further comprising the steps of:
providing a pin guide; establishing the rotation by aligning the
pin guide with one of the femoral posterior condyles, a line drawn
between medial and lateral epicondyles, and a line drawn along the
A/P axis; establishing the A/P position by offsetting the pin guide
from a probe in contact with the anterior surface; and establishing
the datum by guiding at least one pin through the pin guide and
into the femur.
70. The method of claim 69 wherein the step of establishing the
datum comprises guiding at least two pins through the pin guide and
into the femur.
71. The method of claim 65 further comprising the steps of:
referencing the datum with a cut guide to orient the cut guide
relative to the rotation angle and A/P position; and guiding a
cutter with the cut guide to cut the femur.
72. The method of claim 71 further comprising the step of making an
incision on the at least one of the medial and lateral sides of a
knee to expose the femur from the side and performing the other
steps through the incision from the side of the knee.
73. A method for establishing a position reference datum on a
distal portion of a femur having a distal end, an anterior surface,
a posterior surface, a medial side surface, a lateral side surface,
posterior condyles, a femoral axis, and anatomic landmarks, the
method comprising the steps of: providing a guide having a base and
a pin guide mounted for rotation and translation relative to the
base; placing the base against the distal end of said femur;
rotating the pin guide relative to the base to a desired rotation
angle; translating the pin guide relative to the base to a desired
A/P position; and inserting at least one pin into said femur with
the pin guide, the at least on pin fixing the rotation angle and
A/P position for future reference.
74. The method of claim 73 wherein the step of inserting at least
one pin comprises inserting at least two pins.
75. The method of claim 73 further comprising the steps of:
mounting a cut guide on the pin to orient the cut guide at the
desired rotation angle and A/P position; and guiding a cutter with
the cut guide to make anterior, posterior and chamfer cuts on the
distal femur.
76. The method of claim 75 further comprising the steps of: making
an incision on one of the medial and lateral sides of the knee to
expose the femur from the side; and performing the other steps
through the incision from the side of the knee.
77. An apparatus for guiding a cutter to cut a femur having a datum
established on it, the datum fixing a desired external rotation and
A/P position, the apparatus comprising: a cut guide for guiding a
cutter to cut said femur; and means for engaging said datum to
orient the cut guide to guide a cutter to cut said femur at said
desired external rotation and A/P position.
78. The apparatus of claim 77 wherein the cut guide comprises a saw
blade guide.
79. The apparatus of claim 78 wherein the saw blade guide includes
slots for guiding a saw blade to form anterior, posterior, and
chamfer cuts on said femur.
80. The apparatus of claim 79 wherein the guide includes a side
portion and a distal portion, the slots sweeping from the side
portion to the distal portion to allow cutting from the side and
distally.
81. The apparatus of claim 77 wherein the means for engaging said
datum comprises a hole formed in the cut guide.
82. A guide for guiding a cutter to cut a profile on a distal
femur, the femur having at least one pin inserted into the side of
the femur fixing a desired external rotation and A/P position, the
guide comprising: a distal portion having inner and outer distal
surfaces; a side portion having inner and outer side surfaces with
at least one hole extending through the side from the inner to the
outer side surface for receiving said at least one pin to set the
guide at said desired external rotation and A/P position; and a cut
guide for guiding a cutter to cut said femur at said desired
external rotation and A/P position.
83. The guide of claim 82 wherein the cut guide comprises a saw
guide slot.
84. The guide of claim 83 wherein the saw guide slot sweeps from
the side portion to the distal portion.
85. The guide of claim 82 wherein the distal portion further
comprising an opening for visualizing the distal end of the
femur.
86. The guide of claim 82 wherein the at least one hole is slotted
so that the guide can slide between a proximal position and a
distal position on the pin to permit the inner, distal guide
surface to be positioned in contact with said distal femur.
87. The guide of claim 86 further comprising a distal fixation hole
to receive a fastener to fix the guide in a position with the
inner, distal guide surface in contact with said distal femur.
88. A method for cutting a distal portion of a femur having an
anterior surface, a posterior surface, and a femoral axis, the
method comprising the steps of: determining a desired rotation
angle relative to the femoral axis; determining a desired A/P
position between the anterior and posterior surfaces of the femur;
creating a datum on the distal femur that records the rotation
angle and A/P position; referencing the datum with a cut guide to
orient the cut guide relative to the rotation angle and A/P
position; and guiding a cutter with the cut guide to cut the
femur.
89. The method of claim 88 wherein the cut guide comprises a saw
guide slot and the step of guiding a cutter comprises guiding a saw
blade.
90. The method of claim 89 wherein the saw guide slot sweeps from a
side portion to distal portion and further comprising the step of
guiding a saw blade through the slot from the side and moving the
saw blade through the swept slot to guide the saw blade through the
slot distally.
91. The method of claim 88 wherein the cut guide further includes
window for viewing the distal end of the femur and further
comprising the step of viewing the cutting of the distal end of the
femur through the window.
92. The method of claim 88 wherein the datum is a pin and the cut
guide has a hole for receiving the pin, the method further
comprising the step of engaging the pin with the hole to position
the cut guide.
93. The method of claim 92 wherein the hole comprises an elongated
slot to permit the cut guide to slide proximally and distally on
the pin, the method further comprising sliding the cut guide
proximally on the pin until it abuts the distal femur.
94. The method of claim 93 wherein the cut guide further comprises
a distal fixation hole, the method further comprising the step of
inserting a fastener through the fixation hole to hold the cut
guide against the distal femur.
95. The method of claim 88 further comprising the steps of: making
an incision on at least one of the medial and lateral sides of a
knee to expose the femur from the side; and performing the other
steps through the incision from the side of the knee.
96. A cut guide for a femur having an anterior side, a posterior
side, a proximal end, and a distal end, the cut guide comprising:
an anterior body portion having an outer anterior surface, an inner
anterior surface, and an anterior cut guide surface; a distal body
portion having an outer distal surface, an inner distal surface,
and a distal cut guide surface, the distal body portion extending
from the anterior body portion at an angle, the distal cut guide
surface being aligned with the anterior cut guide surface; and a
cutter guidable from the distal cut guide surface to the anterior
cut guide surface to cut the anterodistal aspect of said femur
along an angle from posterior and distal to anterior and
proximal.
97. The cut guide of claim 96 wherein the anterior cut guide
surface comprises an anterior chisel guide and the posterior cut
guide surface comprises a posterior chisel guide and the cutter
comprises a chisel.
98. The cut guide of claim 97 wherein the anterior chisel guide
comprises a slot extending from the outer anterior surface to the
inner anterior surface, the distal chisel guide comprises a slot
extending from the outer distal surface to the inner distal surface
and the chisel comprises a cross sectional shape matching the
anterior and distal chisel slots so that the chisel is insertable
through the chisel slots from the distal chisel slot to the
anterior chisel slot.
99. The cut guide of claim 98 wherein the slots are three sided and
the chisel comprises a corresponding three sided shape.
100. The cut guide of claim 99 further comprising at least one
distal drill guide hole formed through the distal body portion from
the outer distal surface to the inner distal surface to guide a
drill to form at least one hole in the distal end of the femur at a
predetermined location relative to the slots.
101. The cut guide of claim 97 further comprising medial and
lateral articular condyles having articulating surfaces formed
thereon permitting trial fitting of the cut guide to simulate the
fit of a corresponding femoral implant relative to the tibia.
102. The cut guide of claim 101 further comprising a patellar
articular surface formed thereon permitting trial fitting of the
cut guide to simulate the fit of a corresponding femoral implant
relative to the patella.
103. The cut guide of claim 97 further comprising an inner box
profile corresponding to the inner box profile of a femoral
implant.
104. A method for cutting the anterodistal aspect of a femur having
an anterior side, a posterior side, a proximal end, and a distal
end, the method comprising the steps of: mounting a cut guide on
the femur, the cut guide having a chisel guide; and guiding a
chisel with the chisel guide to cut the anterodistal aspect of the
femur along an angle from posterior and distal to anterior and
proximal.
105. The method of claim 104 wherein the chisel guide comprises an
anterior chisel slot and a distal chisel slot and the chisel
comprises a cross sectional shape matching the anterior and distal
chisel slots, the method further comprising the step of inserting
the chisel through the slots from the distal chisel slot to the
anterior chisel slot.
106. The method of claim 105 wherein the cut guide further
comprises at least one drill guide hole, the method further
comprising the step of guiding a drill with the at least one drill
guide hole to drill a hole in the distal end of the femur at a
predetermined location relative to the slots.
107. The method of claim 104 wherein the cut guide further
comprises medial and lateral articular condyles having articulating
surfaces formed thereon, the method further comprising the step of
performing a trial fitting of the cut guide on the femur and
articulating it relative to the tibia to simulate the fit of a
corresponding femoral implant relative to the tibia, before the
step of guiding a chisel to cut the femur.
108. The method of claim 104 wherein the cut guide further
comprises a patellar articular surface formed thereon, the method
further comprising the step of performing a trial fitting of the
cut guide on the femur and articulating it relative to the patella
to simulate the fit of a corresponding femoral implant relative to
the patella, before the step of guiding a chisel to cut the
femur.
109. The method of claim 104 further comprising the steps of first
making an incision on one of the medial and lateral sides of the
knee joint to expose the femur from the side and performing the
other steps through the incision from the side of the knee.
110. The method of claim 104 further comprising the steps of
providing a femoral notch guide comprising a notch cut guide and a
protrusion for engaging the cut in the anterodistal aspect of the
femur, engaging the protrusion with the cut in the anterodistal
aspect of the femur to align the femoral notch cut guide, and
guiding a cutter with the notch cut guide to cut a notch in the
femur.
111. The method of claim 106 further comprising the steps of
providing a femoral notch guide comprising a notch cut guide and at
least one protrusion for engaging the at least one hole drilled in
the distal end of the femur, engaging the protrusion with the hole
in the distal end of the femur to align the femoral notch cut
guide, and guiding a cutter with the notch cut guide to cut a notch
in the femur.
112. A method of total knee arthroplasty comprising the steps of:
making an incision on at least one of the medial and lateral sides
of a knee to expose the knee joint from the side; placing a patella
cut guide adjacent the patella; guiding a cutter with the patella
cut guide through the incision to cut the patella from the side of
the knee; placing a femoral cut guide adjacent the femur; guiding a
cutter with the femoral cut guide through the incision to cut the
femur from the side of the knee; placing a tibial cut guide
adjacent the tibia; and guiding a cutter with the tibial cut guide
through the incision to cut the tibia from the side of the
knee.
113. The method of claim 112 wherein the step of cutting the femur
comprises cutting the distal end of the femur and wherein the
method further comprises the steps of: establishing a datum on the
femur engageable from the side of the knee to fix the desired
external rotation and anteroposterior position of subsequent bone
cuts; engaging the datum with a cut guide to orient the cut guide
in the desired external rotation and anteroposterior position; and
cutting the distal femur profile from the side of the knee.
114. The method of claim 112 wherein the step of cutting the
patella further comprises cutting the patella while maintaining the
patella in its normal anteroposterior orientation relative to the
femur.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0001] Various embodiments of the present invention will be
discussed with reference to the appended drawings. These drawings
depict only illustrative embodiments of the invention and are not
to be considered limiting of its scope.
[0002] FIG. 1 is a front elevation view of a tibia and a femur
showing axes of the knee joint.
[0003] FIG. 2 is a side section view of a knee joint showing
typical bone cuts used in replacing the joint surfaces.
[0004] FIG. 3 is a perspective view of knee joint showing aspects
of component positioning.
[0005] FIG. 4 is a perspective view of the knee joint showing the
incision planning for a medial surgical approach according to the
present invention.
[0006] FIG. 5 is a perspective view of the knee joint showing the
medial incision according to the present invention.
[0007] FIG. 6 is a perspective view of the knee joint showing the
incision planning for a lateral surgical approach according to the
present invention.
[0008] FIG. 7 is a perspective view of the knee joint showing the
lateral incision according to the present invention.
[0009] FIG. 8 is a perspective view of an illustrative embodiment
of a patella resection guide according to the present
invention.
[0010] FIG. 9 is a top plan view of the patella resection guide of
FIG. 8.
[0011] FIG. 10 is an exploded perspective view of another
illustrative embodiment of a patella resection guide according to
the present invention.
[0012] FIG. 11 is a top plan view of the patella resection guide of
FIG. 10.
[0013] FIG. 12 is a side elevation view of the patella resection
guide of FIG. 10 shown gripping a patella.
[0014] FIG. 13 is a front elevation view of the patella resection
guide of FIG. 10.
[0015] FIG. 14 is a perspective view of an illustrative embodiment
of an intramedullary distal femoral cutting instrument according to
the present invention.
[0016] FIG. 15 is a side elevation view of the intramedullary
distal femoral cutting instrument of FIG. 14.
[0017] FIG. 16 is a front elevation view of the intramedullary
distal femoral cutting instrument of FIG. 14.
[0018] FIG. 17 is a side elevation view of the intramedullary
distal femoral cutting instrument of FIG. 14 mounted on a
femur.
[0019] FIG. 18 is a side elevation view of another illustrative
intramedullary distal femoral cutting instrument according to the
present invention mounted on a femur.
[0020] FIG. 19 is a front elevation view of an illustrative
embodiment of a tibial cut guide assembly according to the present
invention.
[0021] FIG. 20 is a perspective view of the tibial cut guide
assembly of FIG. 19.
[0022] FIG. 21 is a top plan view of the tibial cut guide assembly
of FIG. 19.
[0023] FIG. 22 is an exploded perspective view of an illustrative
embodiment of a depth gauge for use with the tibial cut guide of
FIG. 19 according to the present invention.
[0024] FIG. 23 is a perspective view of the tibial cut guide
assembly of FIG. 19 and the depth gauge of FIG. 22 mounted on a
tibia.
[0025] FIG. 24 is a perspective view of an illustrative embodiment
of a femoral A/P sizer and pin guide assembly according to the
present invention.
[0026] FIG. 25 is a bottom plan view of the femoral A/P sizer and
pin guide assembly of FIG. 24.
[0027] FIG. 26 is a perspective view, from a different viewing
angle, of the femoral A/P sizer and pin guide assembly of FIG.
24.
[0028] FIG. 27 is a perspective view showing the femoral A/P sizer
and pin guide assembly of FIG. 24 being assembled on a distal
femur.
[0029] FIG. 28 is a perspective view showing the femoral A/P sizer
and pin guide assembly of FIG. 24 fully assembled on a distal
femur.
[0030] FIG. 29 is a perspective view showing two reference pins
inserted in the distal femur using the femoral A/P sizer and pin
guide assembly of FIG. 24.
[0031] FIG. 30 is a perspective view of an illustrative embodiment
of a femoral profile cut block according to the present
invention.
[0032] FIG. 31 is a perspective view, from a different viewing
angle, of the femoral profile cut block of FIG. 30.
[0033] FIG. 32 is a perspective view of the femoral profile cut
block of FIG. 30 mounted on a femur.
[0034] FIG. 33 is a perspective view of an illustrative embodiment
of a trochlear cut guide according to the present invention.
[0035] FIG. 34 is a perspective view of another illustrative
embodiment of a femoral provisional trochlear cut guide according
to the present invention mounted on a femur and further showing an
illustrative embodiment of a chisel for use with the cut guide.
[0036] FIG. 35 is a side elevation view of the intercondylar notch
guide of FIG. 39.
[0037] FIG. 36 is a perspective view of an illustrative embodiment
of an intercondylar notch guide mounted on a femur according to the
present invention.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0038] The present invention relates to methods and instruments for
performing total knee arthroplasty. An incision is made into the
knee joint to expose the bones comprising the joint. Cutting guides
are then used to guide the removal of the articular surfaces that
are to be replaced. Artificial joint components are then positioned
to replace the resected bone ends in order to establish the desired
alignment and mechanics of the joint. Each aspect of the surgery
affects the ultimate outcome of the procedure. The incision
location and size determines the extent to which the bones can be
exposed for facilitating the bone cutting steps. The incision also
affects the amount of trauma to the soft tissues surrounding the
joint and therefore the pain, time for recovery, and stability of
the joint postoperatively. The design of the cutting guides affects
how much exposure is required to place and orient the guides
relative to the bones. The precision of the cuts produced by the
guides affects the stability and longevity of the joint
replacement. Finally, the manner in which the joint components
attach to one another and to the bone affects the amount of
exposure required and the stability and longevity of the joint
replacement. The inventive instruments and method are generally
suitable for knee joint surgery. Furthermore, they include features
that make them suitable for performing a minimally invasive knee
surgery in which a smaller than normal incision is made and
oriented to preserve the quadriceps mechanism and protect the
suprapatellar pouch. The instruments permit switching from a
minimally invasive technique to a standard open technique at any
point in the procedure.
[0039] In order to better understand the total knee arthroplasty
procedure, it is helpful to understand the relationship of the
bones and the cuts made to orient the implant components. FIGS. 1-3
illustrate several aspects of implant orientation. FIG. 1
illustrates various axes of the lower limb in the frontal plane.
Axes can be defined for each segment of the lower limb. For
example, the femur 1 has an anatomic axis 2 coinciding generally
with its intramedullary canal. It also has a mechanical axis 4, or
load axis, running from the center of the femoral head to the
center of the knee. The angle 6 between these two axes varies
within the patient population but is on the order of 6.degree..
Likewise, the tibia 3 has an anatomic axis coinciding generally
with its intramedullary canal. The mechanical axis 5 of the tibia
runs from the center of the knee to the center of the ankle and is
generally collinear with the anatomic axis. The transverse axis, or
joint line 8, about which the knee flexes, is parallel to a line
through the medial and lateral femoral condyles and parallel to the
tibial plateau. This line subtends a slight valgus angle of
approximately 87.degree. with the mechanical axis of the femur and
a slight varus angle of approximately 87.degree. with the
mechanical axis of the tibia. Thus, the distal femur is in slight
valgus and the proximal tibia is in slight varus. Normally, the
distal femur and proximal tibia are resected to be parallel to the
joint line 8, and thus perpendicular to the mechanical axis 4, as
indicated at 10 and 12. The intersection of the femoral and tibial
mechanical axes, 4 and 5, may subtend a small angle relative to one
another. However, the angle is small and the mechanical axis of the
femur has an approximately normal alignment with the proximal tibia
if the knee is uninjured. Therefore the tibial mechanical axis may
be extrapolated to the distal femur to define the femoral
mechanical axis in the distal femur when there is a femoral
deformity. Similarly, if there is a deformity in the tibia, the
mechanical axis of the proximal tibia may be defined by
extrapolating the femoral mechanical axis. The illustrative
procedure described herein restores the center of the femoral bead,
the knee, and the ankle to a lie on a straight line to establish a
neutral mechanical axis. The femoral and tibial components are
oriented perpendicular to this axis in the frontal plane.
[0040] FIG. 2 illustrates the knee joint from the side or sagittal
view and various bone cuts that may be made to align implant
components. The distal femur is typically cut 10 perpendicular, in
the anterior-to-posterior direction, to the anatomic axis 2 of the
femur. The proximal tibial resection 12 is normally cut to match
the natural posterior slope of the proximal tibia relative to the
tibial mechanical axis 5. The amount of posterior slope 16 relative
to a reference line 18 perpendicular to the tibial mechanical axis
5 varies in the patient population but is on the order of
7.degree.. The distance between the distal femoral 10 and proximal
tibial 12 cuts along the mechanical axes 4 and 5 is the extension
gap. Other cuts may be made depending on the components that are to
be implanted. These include an anterior femoral cut 20, anterior
femoral chamfer cut 22, posterior femoral chamfer cut 24, and
posterior femoral cut 26. The patella 7 may also be cut 28 to allow
for replacement of the patellar articular surface. Additional
preparation of the bone may include drilling or notching the bones
to receive pegs, stems, and other extensions from the components
(not shown).
[0041] FIG. 3 depicts six aspects of component positioning relative
to a coordinate system in which the x-axis 30 corresponds
approximately to the joint line 8, the z-axis 34 corresponds
approximately to the mechanical axes 4 and 5, and the y-axis 32 is
normal to the other two. Position along each of these axes is
depicted by arrows. Position along the x, y, and z axes determines
the medial/lateral (dx) 36, anterior/posterior (dy) 38, and
proximal/distal (dz) 40 positioning of components respectively.
Rotation about each of these axes is also depicted by arrows.
Rotation about the z-axis (rz) 42 corresponds anatomically to
external rotation of the femoral component, while rotation about
the x-axis (rx) 44 and y-axis (ry) 46, corresponds to extension
plane slope and varus/valgus angle respectively. Depending on the
order of the cuts, and the way that subsequent instruments
reference each cut, the position of the distal femoral cut 10 can
affect the location of the joint line (dz), the extension gap, the
varus/valgus angle (ry), and the extension plane angle (rx).
Likewise, the position of the proximal tibial cut 12 can affect the
varus/valgus angle (ry), extension plane (rx), external rotation
(rz), and the joint line (dz) or extension gap. The position of the
anterior 20, posterior 26, and chamfer 22 and 24 femoral cuts
affect anterior/posterior size and placement (dy) and external
rotation (rz). Finally, the position of peg holes, stem notches,
and other similar bone cuts affect medial/lateral (dx) placement of
components.
[0042] An illustrative set of instruments for total knee
arthroplasty and an associated minimally invasive technique will
now be described with reference to the drawings. The illustrative
technique utilizes a limited exposure approach from the side of the
knee as shown in FIGS. 4-7. This side approach can be at an oblique
angle relative to the front of the knee or transversely, more
directly from the side. The side approach permits a minimally
invasive knee surgery in which a smaller than normal incision is
made and orients the incision and subsequent bone cuts to preserve
the quadriceps mechanism and protect the suprapatellar pouch. FIGS.
4 and 5 depict a medial approach and FIGS. 6 and 7 depict a lateral
approach. Reference lines are made on the knee prior to making the
incision. For the medial approach, a curvilinear medial incision 50
is made from the superior pole 52 of the patella 54 to the tibial
joint line 56. The outline of the medial femoral condyle 58 is also
marked. The arthrotomy is in line with the skin incision and
includes a transverse incision 60 beneath the vastus medialis to
increase the exposure of the medial femoral condyle 62.
Alternatively, a lateral approach may be used. For the lateral
approach, the incision 70 is made on the lateral side of the
patella 72 to the tibial joint line 74 and is almost vertical along
the side of the patella. The outline of the lateral femoral condyle
75 is also marked. The arthrotomy is performed in a vertical
fashion and the iliotibial band 76 is peeled from the tibial
plateau joint line from anterior to posterior to expose the lateral
femoral condyle 78. No transverse capsular incision is used for the
lateral approach.
[0043] Throughout the description of the illustrative technique and
instruments, reference will be made to cutting bone. There are many
cutters for surgically cutting bone including: oscillating saws,
reciprocating saws, gigli saws, end cutting reamers, side cutting
reamers, streams of particles, energy beams, and others known in
the art. While the illustrative embodiments depict and describe saw
blade guides for guiding a saw blade to cut bone, any means for
cutting bone is contemplated. The slots can be replaced with
surfaces, jigs, clamps, and other types of fixtures as appropriate
to guide the type of cutter being used.
[0044] The preparation of the patella is described first. However,
the patella can be prepared later if desired. Preparing it first
results in more space anteriorly when preparing the distal femur.
The illustrative instruments allow preparation of the patella
without everting it to avoid damage to the patellar mechanism.
Alternatively, waiting until after the distal femur and/or proximal
tibia are prepared allows the joint to be collapsed to reduce
tension in the patellar tendon and ligament and improve access to
prepare the patella.
[0045] The patella is prepared using a patella resection guide.
FIGS. 8 and 9 illustrate one embodiment of a patella resection
guide 100. Stationary jaw member 102 includes a top surface 104, a
bottom surface 106, an inner concave surface 108, an opposite outer
surface 109, and teeth 110 projecting inwardly from the concave
surface 108, adjacent the top surface 104. Guide arms 112, 114
project from the concave surface 108 and connect the concave
surface to a pair of handles 116, 118. The guide arms 112, 114 are
generally perpendicular to the jaw member 102 and parallel to one
another. The pair of handles 116, 118 are coplanar and are attached
generally perpendicularly to the guide arms 112, 114 and extend in
opposite directions from one another. A top portion 111 of the
stationary jaw 102, including the teeth 110 and top surface 104,
projects above the guide arms 112, 114. Translating jaw member 122
includes a top surface 124, a bottom surface 126, an inner concave
surface 128, an opposite outer surface 129, and teeth 130
projecting inwardly from the concave surface 128, adjacent the top
surface 124. Bores 131, 132 through the translating jaw member 122
provide bearing surfaces in engagement with guide arms 112, 114
such that the translating jaw member 122 may be moved along the
guide arms 112, 114 in a motion plane from a first position in
which the two jaw members 102, 122 are spaced from one another and
the translating jaw 122 is nearer the handles 116, 118 and a second
position in which the two jaw members 102, 122 are closer to one
another and the translating jaw 122 is farther from the handles
116, 118. This arrangement constrains the jaws to remain parallel
to one another as they move relative to one another. A top portion
134, including the teeth 130 and top surface 124, of the
translating jaw 122 projects above the guide arms 112, 114 such
that the tops 104, 124 of the jaws 102, 122 are coplanar. The
translating jaw 122 further includes a saw guide slot 135 extending
through the top portion 134 from the outer surface 129 to the inner
concave surface 128 parallel to the top surface 124 and extending
beyond the attachment point of the guide arms to the handles on
either side. The slot 135 is positioned so that it is above the
level of the handles 116, 118 to permit easy access for the
insertion of a saw blade anywhere across the entire width of the
slot 135. The slot 135 defines a cutting plane parallel to the
motion plane of the translating jaw 122. Actuator 136 comprises an
elongate lever having a jaw engaging end 138, a pivot portion 140,
and an input end 142. The jaw engaging end 138 further includes a
slot 144 through which a pin 146 connects the jaw engaging end 138
to the translating jaw 122. The jaw engaging end 138 can pivot and
translate via the slot 144 relative to the pin 146 which is fixed
to the translating jaw 122. The actuator 136 is pivotally
constrained by a pin 148 extending through the pivot portion 140
and being fixed to the handle 118. Input end 142 extends at an
angle to the handle 118 when the jaws 102, 122 are in a first
position in which they are spaced from one another. In use, a user
grips the handles 116, 118 and squeezes the input end 142 of the
actuator 136 to reduce the angle between the input end 142 and the
handle 118. As the actuator pivot portion 140 rotates about its pin
148, the jaw engaging end 138 presses against its pin 146 and moves
the translating jaw 122 toward the stationary jaw 102.
[0046] FIGS. 10-13 illustrate another embodiment of a patella
resection guide 200. Stationary jaw member 202 includes a top
surface 204, a bottom surface 206, a concave inner surface 208, an
opposite convex outer surface 209, and teeth 210 projecting
inwardly from the concave surface 208, adjacent the top surface
204. Guide arms 212, 214 project from the concave surface 208 and
connect the concave surface to a pair of handles 216, 218 via
rectangular bosses 215, 217. The guide arms 212, 214 are generally
perpendicular to the jaw member 202 and parallel to one another.
The handles 216, 218 are coplanar and are attached generally
perpendicularly to the guide arms 212, 214 and extend in opposite
directions from one another. In this embodiment, the guide arms
212, 214 extend past their connections 215, 217 to the handles 216,
218. A top portion 211, including the teeth 210 and top surface
204, of the stationary jaw 202 projects above the guide arms 212,
214. A translating jaw member 222 includes a top surface 224, a
bottom surface 226, an inner concave surface 228, an opposite
convex outer surface 229, and teeth 230 projecting inwardly from
the concave surface 228, adjacent the top surface 224. Cannulated
guide sleeves 221, 223 connect to opposite sides of the translating
jaw 222 and connect the concave surface 228 to a pair of handles
231, 233. The guide sleeves 221, 223 are coplanar and are generally
perpendicular to the translating jaw 222 and parallel to one
another. The pair of handles 231, 233 are attached generally
perpendicularly to the guide sleeves 221, 223 and extend oppositely
and outwardly from the translating jaw 222. The guide sleeves 221,
223 have outwardly facing slots 225, 227 in their outer wall
communicating with their inner cannulac. The guide sleeves 221, 223
receive guide arms 212, 214 such that the translating jaw member
222 may be moved along the guide arms 212, 214 from a first
position in which the two jaw members 202, 222 are spaced from one
another and the translating handles 231, 233 are spaced from the
stationary handles 216, 218 and a second position in which the jaw
members and handles are closer to one another. This arrangement
constrains the jaw members to remain parallel and facing one
another while they move relative to one another. A top portion 234,
including the teeth 230 and top surface 224, of the translating jaw
222 projects above the guide sleeves 221, 223 such that the tops
204, 224 of the jaws 202, 222 are coplanar. The translating jaw 222
further includes a saw guide slot 235 extending through the top
portion 234 from the outer surface 229 to the inner surface 228
parallel to the top surface 224.
[0047] This embodiment further includes a depth gauge 240 having a
support 242 and blade 244. The support 242 includes a blade
engaging end 246, a resection guide engaging end 248, and a
longitudinal axis from one end to the other. The blade includes
first 250 and second 252 ends and center attachment portion 254.
The center attachment portion 254 is attached to the blade engaging
end 246 of the support 242 with a threaded post extending from the
support 242 through the attachment portion 254 and secured with a
nut 255. The first 250 and second 252 blade ends are each offset a
different distance from the center attachment portion 254 measured
along the support 242 axis. The resection guide engaging end 248
and the resection guide 200 include an engagement mechanism for
selectively attaching the depth gauge 240 to the resection guide
200. Translating jaw 222 includes a through bore 256 extending from
the top surface 224 to the bottom surface 226 in communication with
the guide slot 235. Depth gauge support 242 includes a hole 258
retaining a spring 260 and ball 262 plunger in the resection guide
engaging end 248. The ball 262 is biased into engagement with the
guide slot 235 when the resection guide engaging end 248 is
inserted into through bore 256. The depth gauge can engage the
through bore 256 and be supported on either the top surface 224 or
bottom surface 226. When it is thus supported, the blade ends 250,
252 can be selectively placed to project over the jaws 202, 222.
Each blade end projects to define a plane a different predetermined
axial distance from the guide slot 235.
[0048] Both illustrative embodiments are relatively compact to
permit the stationary jaw to be wedged across the joint between the
femur and patella. Both also facilitate approaching the patella
from the lateral or medial side and gripping it on its sides while
presenting an unobstructed side-facing saw guide slot. The use of
the instrument will be described relative to the embodiment of
FIGS. 10-13. The surgeon first determines whether it is desirable
to remove a prescribed amount of patellar bone or to leave a
prescribed amount and how much in either case. To remove a
prescribed amount of bone, the depth gauge 240 is attached to the
top surface 224 of the translating jaw 222 so that the blade 244
references the posterior side 272 of the patella 270 as shown in
FIG. 12. To leave a prescribed amount of bone, the depth gauge 240
is attached to the bottom surface 226 of the translating jaw 222 so
that the blade 244 references the anterior side 274 of the patella
270. The amount is established by positioning the blade end 250 or
252 having the corresponding amount of offset in contact with the
patella. The stationaryjaw 202 is wedged across the joint between
the femur and patella with the top surface 204 facing toward the
posterior side 272 of the patella 270 and the bottom surface 206
facing toward the femur. The patella 270 is placed between the jaws
with the depth gauge blade in contact with the appropriate patellar
surface and the handles 218, 233 and 216, 231 are gripped and
squeezed toward one another to bring the jaws 202,222 together to
grip the patella 270 medially and laterally. A saw blade is
activated through the saw guide slot 235 to resect the patella. A
locking mechanism can be provided to selectively prevent the jaws
from moving away from one another. For example, the guide arms 212,
214 can be threaded and provided with nuts at their free ends.
After the translating jaw is moved toward the stationary jaw, the
nuts would be advanced to prevent the translating jaw from moving
backward. Likewise, the guide arms 212, 214 can be grooved and the
guide sleeves 221, 223 provided with ratcheting palls biased into
engagement with the grooves such that the palls ride freely over
the grooves as the jaws are moved toward one another but the palls
engage the grooves and resist motion of the jaws away from one
another.
[0049] The distal femur is prepared using a distal femoral cut
guide. FIGS. 14-17 show an illustrative embodiment of an
intramedullary (IM) distal femoral cutting instrument 300 for
guiding the distal femoral cut. An IM alignment guide 302 includes
a body 304 having front 306 and back 308 surfaces, lateral 310 and
medial 312 ends, and first 309 and second 311 side surfaces. A
through slot 314 communicates from the front surface 306 to the
back surface 308. A cut guide engaging slot 316 extends part way
from the back surface 308 toward the front surface 306. The cut
guide engaging slot 316 is generally aligned with the through slot
314 and is wider than the slot 314 side-to-side. The cut guide
engaging slot 316 extends laterally to open at the lateral end 310.
A neck 318 projects from the medial end 312 and extends the back
surface 308 medially. A lug 320 is connected to the end of the neck
318 opposite the body 304. The lug includes a rounded reference
surface 322 that projects beyond the back surface 308. A socket
324, having a longitudinal axis, is formed in the reference surface
322. The axis of the socket 324 forms a predetermined angle
relative to the back surface 308. For a medial approach to the
knee, the angle will be obtuse and for a lateral approach it will
be acute. An intramedullary rod 326 having a longitudinal axis fits
into the socket 324 so that the rod 326 axis is coaxial with the
socket axis and extends from the IM alignment guide at the
predetermined angle. The rod 326 is welded in place.
[0050] An IM distal cut guide 330 includes a body 332 with front
334 and back 336 surfaces, medial 338 and lateral 340 surfaces, and
first 342 and second 344 sides. Three saw blade slots 345 extend
through the cut guide 330 from the medial 338 to the lateral 340
surface. The slots 345 lie in planes parallel to the front surface
334. A pin tab 346 extends from the back surface 346 and has
lateral 348 and medial surfaces 350 that taper 353 inwardly from
the medial 338 and lateral 340 surfaces of the body. Fixation holes
351 extend through the pin tab from the lateral surface 348 to the
medial surface 350. An engagement tab 352 extends from the front
surface 334 and has sides 354 and 356 and front surface 358. A
threaded hole 360 extends from the front surface 358 toward the
body 332. The engagement tab 352 engages the cut guide engaging
slot 316 with the front surface 334 of the distal cut guide resting
against the back surface 308 of the IM alignment guide such that
the saw blade slots 345 are parallel to the back surface 308 and
thus are at the predetermined angle relative to the IM rod 326. The
plane of the middle saw blade slot intersects the extreme end of
the reference surface 322. It is desirable to resect the distal
femur perpendicular to the mechanical axis of the femur. Therefore,
the distal cut guide is aligned such that a line perpendicular to
the saw blade slots 345 is aligned with the mechanical axis. This
is accomplished by providing a plurality of IM alignment guides
having the angle of the IM rod 326, relative to the plane of the
saw blade slots 345, equal to the difference between the anatomic
and mechanical axes of the femur. Because of variation in the
patient population, IM alignment guides having different rod 326
angles are provided. For example, angles of 4.degree., 6.degree.,
and 8.degree. have been found to be suitable to accommodate most
patients. The engagement of the tab 352 and slot 316 allows the
distal cut guide 330 to slide relative to the IM alignment guide
302 from a first position in which the distal cut guide 330 is
farther from the IM rod 326 and a second position in which the
distal cut guide 330 is nearer to the IM rod 326. A handle 361
includes a grip portion 362, a threaded stud 363 opposite the grip
portion 362, and a shoulder 364 intermediate the grip portion 362
and the threaded stud 363. The threaded stud 363 extends through
the slot 314 in the IM alignment guide 302 to threadingly engage
the threaded hole 360 in the engagement tab 352 of the distal cut
guide 330. As the handle 361 is rotated to further engage the
threaded hole 360, the shoulder 364 bears against front surface 306
of the IM alignment guide 302 and the front surface 334 of the
distal cut guide 330 is drawn into tight locking engagement with
the back surface 308 of the IM alignment guide 302. By means of the
handle 361, the distal cut guide 330 can be slid and locked at any
position of its travel along the IM alignment guide.
[0051] In use, a hole is drilled in the center of the patellar
sulcus 366 of the distal femur, making sure that the hole is
parallel to the shaft of the femur 365 in both the frontal and
sagittal planes. The hole provides access to the IM canal of the
femur 365. An IM alignment guide 302 is selected as appropriate for
a medial or lateral approach and having a rod 326 angle that
accounts for the difference between the anatomic and mechanical
axes of the femur as determined by preoperative templating. The IM
distal cut guide 330 is attached to the alignment guide 302 using
the handle 361. Using the handle, IM rod 326 is inserted into the
IM canal of the femur 365. The assembly is inserted until the
reference surface 322 contacts the intercondylar sulcus 366 with
the IM alignment guide 302 projecting toward the exposed side of
the knee. The distal cut guide 330 is slid in slot 316 until the
medial surface 338 is adjacent the bone. In FIG. 17, the distal cut
guide 330 is shown adjacent the medial condyle 367. The handle 360
is rotated to lock the distal cut guide 330 relative to the IM
alignment guide 302. Pins 368 are then inserted through the holes
351 in the pin tab 346 and into the bone to hold the distal cut
guide 330 in place. The taper 353 of the medial side 350 of the pin
tab 346 causes it to fit the condylar bone more closely and
therefore more stably. Once the pins are placed, the handle 361 is
unthreaded from the distal cut guide 330 and the IM alignment guide
302 and IM rod 326 are removed from the bone leaving the distal cut
guide 330 pinned to the bone. A saw blade is then directed through
one of the slots 345 to resect the distal femur. If the reference
surface 322 was fully seated in the intercondylar sulcus 366, the
middle saw guide slot will resect the distal femur to the depth of
the sulcus. The other slots provide more or less resection.
[0052] FIG. 18 shows an alternative embodiment of distal femoral
cut guide 300 in which the lug 320 and rounded reference surface
322 have been omitted. Instead, an IM rod 370 is connected directly
to the end 372 of the neck 374 of the IM alignment guide. In this
embodiment, the IM rod 370 is inserted into the IM canal of the
femur 378 until the back surface 380 contacts the near distal
femoral condyle. In this case the back surface 380 contacts the
distal medial condyle 382. The plane of the middle saw blade slot
is offset 10 mm from the back surface 380. The other slots are
offset 6 mm and 14 mm respectively. Thus, the appropriate slot is
chosen based on how much bone is to be resected from the distal
femur relative to the near condyle. Typically, the middle or 10 mm
slot would be used with a medial approach and less would be used
with a lateral approach.
[0053] The proximal tibia is prepared using a tibial cut guide.
FIGS. 19-23 show an illustrative embodiment of a tibial cut guide
assembly 400 for guiding the proximal tibial cut. The assembly
includes a tibial tubercle alignment bar 402, a tibial boom 430, a
tibial cut guide 446, and a tibial depth gauge 484 (FIGS. 22-23).
The tibial tubercle alignment bar 402 includes an elongate body 404
having an anterior face 406, a posterior face 408, first and second
side walls 410, 412, a distal end 414, a proximal end 416, and a
longitudinal axis running from the distal end to the proximal end.
A dovetail 417 is formed on a portion of the alignment bar 402
adjacent the anterior face 406. A stop 418 projects from the
anterior face 406 near one end of the dovetail 417 toward the
distal end 414 of the alignment bar 402. Extensions 420 project
perpendicularly from either side 410, 412 of the body 404 near the
proximal end 416. Fixation holes 421 are formed through the
extensions 420 from anterior to posterior for receiving fixation
pins. A threaded bore 422 extends through the alignment bar 402
from the anterior face 406 to the posterior face 408 near the
proximal end 416. A plunger 424 having a threaded shaft 426 and an
adjustment knob 427 is received in the threaded bore 422 such that
rotating the adjustment knob 427 moves the plunger 424 anteriorly
and posteriorly to change the spacing from the end of the plunger
424 to the posterior face 408. A cannula 428 extends through the
plunger 424, shaft 426, and knob 427 to allow a pin to pass.
[0054] A tibial boom 430 includes a body 431 having an anterior
face 432, a posterior face 433, a proximal end 434, a distal end
435, and first and second sides 436, 437. A boss 438 projects from
the anterior face and a dovetail groove 439 is formed into the
posterior face. A threaded bore is formed through the boss 438 from
the anterior face 432 to the dovetail groove 439. A set screw 440
is received in the threaded bore such that rotating the set screw
440 moves it into and out of the dovetail groove 439. Extension
bars 442 extend from the first and second sides 436, 437. The
extension bars 442 are "D"-shaped in that they are generally
cylindrical with a flat 443 along one side. The extension bars 442
define a longitudinal axis along their length that is perpendicular
to the dovetail groove 439. The tibial boom 430 is mounted on the
alignment bar 402 with the dovetail groove 439 engaging the
alignment bar dovetail 417 such that the boom 430 can translate
along the longitudinal axis of the alignment bar between a first
position nearer the proximal end 416 of the alignment bar 402 and a
second position further from the proximal end 416 of the alignment
bar 402. The set screw 440 is operable to lock the tibial boom 430
in place by turning the set screw 440 so that it moves into the
dovetail groove 439 to engage the dovetail 417. When the tibial
boom is unlocked, it can slide freely distally until it abuts the
stop 418 which prevents it from sliding further distally. In this
way, the tibial boom 430 can be left unlocked and resting against
the stop 418 ready to be moved into position. The longitudinal axis
of the tibial tubercle alignment bar 402 and the longitudinal axis
of the extension bars 442 together define a guide plane.
[0055] A tibial cut guide 446 includes a cutting head 448 having a
proximal face 450, a distal face 452, opposite side faces 454, 456,
a concave posterior face 458, and a convex anterior face 460. A saw
guide slot 462 extends through the cutting head 448 from the
anterior face 460 to the posterior face 458 generally parallel to
the proximal face 450. Fixation holes 464, 466 also extend through
the cutting head 448 from anterior to posterior. The smaller holes
464 are sized to receive conventional fixation pins, while the
larger hole 466 is sized to receive a spring pin. Proximal face 450
includes a through bore 468 extending from the proximal face 450 to
at least the saw guide slot 462 for receiving a depth gauge. In the
illustrative embodiment, the bore 468 extends all the way through
the cutting head 448 to ease assembly and cleaning. The cutting
head 448 is supported on a base 472 by a leg 474. The base 472 is a
cylinder having a longitudinal axis and proximal 471 and distal 473
faces. Two pairs of "D"-shaped transverse bores 480,482 extend
through the base 472 perpendicular to its longitudinal axis, the
flat portion of the "D"-shaped holes also being perpendicular to
the base axis. A threaded axial bore 476 in the distal face 473
communicates with the path of the "D"-shaped holes 480, 482 and
receives a set screw 478. The leg 474 attaches to the base 472
adjacent the proximal face 471 and angles away from the base 472 to
support the cutting head 448 in a position offset from the base 472
axis with the saw guide slot 462 defining a cutting plane
perpendicular to the longitudinal axis of the base 472.
[0056] The tibial cut guide 400 is provided with a depth gauge 484
having a support 485 and a blade 486. The support 485 includes a
blade engaging end 487, a resection guide engaging end 488, and a
longitudinal axis from one end to the other. The blade 486 includes
first 489 and second 490 ends and a center attachment portion 491.
The center attachment portion 491 is attached to the blade engaging
end 487 with a threaded post 496 extending from the support 485
through the attachment portion 491 and secured with a nut 492. The
first 489 and second 490 blade ends are each offset a different
distance from the center attachment portion 491 measured along the
support 485 axis. The depth gauge support 485 includes a hole 493
retaining a spring 494 and ball plunger 495. The ball 495 is biased
into engagement with the guide slot 462 when the resection guide
engaging end 488 is inserted into the through bore 468. When it is
thus supported, the blade ends 489, 490, can be selectively
positioned to project posteriorly over a tibial bone. Each blade
end projects to define a point a different predetermined axial
distance above the saw guide slot 462.
[0057] The tibial cut guide 446 is assembled to the tibial boom 430
by sliding one of the "D"-shaped extension bars 442 through one
pair 482 of the "D"-shaped holes 480,482. One pair of holes 482
provides for a left knee medial/right knee lateral orientation
while the other 480 provides for a left knee lateral/right knee
medial orientation. Thus assembled, the cutting head 448 is
supported in a position proximal and posterior to the base 472. The
set screw 478 can be tightened until it engages the flat 443 of the
extension bar 442 to lock the cut guide 446 in position on the
extension bar 442. Thus locked, the longitudinal axis of the base
472 is perpendicular to the flat 443 of the extension bar 442
resulting in the saw guide slot 462 being parallel to the flat 443.
The angle of the flat 443, and thus the saw guide slot, relative to
the guide plane defined by the alignment bar 402 and extension bar
442 axes is the posterior slope angle of the tibial cut guide
assembly 400. Tibial booms 430 providing varying degrees of
posterior slope may be provided. For example, having two booms 430,
one with the flat 443 rotated 3.degree. and the other with the flat
rotated 7.degree. would allow the surgeon to choose to cut the
tibia with 3.degree. or 7.degree. of posterior slope.
[0058] In use, a tibial boom 430 is selected having the desired
posterior slope angle. The tibial boom is assembled to the
alignment bar 402 and allowed to slide all the way down to rest on
the stop 418. The plunger 424 is positioned proximal of the tibial
tubercle and centered mediolaterally with the medial third of the
tibial tubercle. A pin is inserted through the cannula 428 of the
plunger 424 to stabilize the alignment guide. Alternatively, a pin
can be placed proximal of the tibial tubercle and centered
mediolaterally with the medial third of the tibial tubercle and the
cannula 428 then slipped over the pin until the plunger 424
contacts the patient. The distal end 414 of the alignment bar 402
is adjusted mediolaterally so that the guide is aligned with the
mechanical axis of the tibia. In the sagittal plane, the alignment
bar 402 is adjusted so that it is parallel to the anterior tibial
shaft. Proximally, this adjustment is made by turning the knob 427
to move the plunger 424 anterioposteriorly. Additional pins are
placed through fixation holes 421 to further secure the alignment
bar 402. This establishes the position of the guide plane relative
to the tibia. Now, as the tibial cut guide 446 is positioned along
the boom 430 and the boom is adjusted up and down, the saw guide
slot 462 will be constrained to parallel planes of posterior slope
having the same angular relation to the guide plane. Thus, the
tibial cut guide 446 can now be adjusted medial-laterally and
proximal-distally without changing the varus-valgus orientation or
the posterior slope of the resection plane.
[0059] The tibial cut guide 446 is assembled to the tibial boom
using the appropriate pair of holes 480, 482 for medial/lateral
orientation of the cut guide 446. The tibial depth gauge 484 is
inserted into the top of the tibial cut guide 446 with the blade
end 489, 490 corresponding to the desired resection level oriented
over the tibia. The tibial cut guide 446 is positioned by moving
the tibial boom 430 vertically until the depth gauge 484 references
the desired spot on the tibial surface and sliding the cut guide
medial-laterally on the extension bar 442 so that it is adjacent
the tibia. This position is maintained by tightening the boom set
screw 440 and the cut guide set screw 478. Pins and/or screws can
then be placed in fixation holes 464, 466 to stabilize the tibial
cut guide. The depth gauge is removed and a saw blade is inserted
through the saw guide slot 462 to cut the proximal surface of the
tibia.
[0060] FIGS. 24-29 show an illustrative embodiment of a femoral A/P
sizer assembly 500 for determining femoral anterior/posterior (A/P)
size and placing reference datums for guiding the femoral box cuts.
The assembly includes an A/P sizer base 502, an external rotation
plate 525, an A/P sizing tower 540, an anterior boom 550, a drill
guide slide 560, a parallel pin drill guide 570, and an alignment
pin 579. The A/P sizer base 502 includes a plate-like body 503
having a front surface 504, a back surface 505, an anterior edge
506, a posterior edge 507, and side surfaces 508,509. Posterior
condyle referencing feet 510, 511 extend perpendicularly from the
front surface 504 and define a posterior reference plane with their
top surfaces 512 and 513. Internally threaded boss 514 projects
from one side 508 of the sizer base 502 to threadably receive a
handle 515. Three alignment holes 516 extend through the sizer base
502 from the front surface 504 to the back surface 505. A
countersunk pivot pin hole 517 extends through the sizer base 502
from the front surface 504 to the back surface 505. An anterior
extension 518 projects from the anterior edge 506 to support a
hollow, cylindrical tower bushing 519 having a top surface 521 and
a bore 520 with a longitudinal axis parallel to the front and back
surfaces 504, 505 and perpendicular to the posterior condyle
referencing feet 510, 511. A through hole in the side of the tower
bushing 519 receives a set screw 522 in communication with the bore
520.
[0061] An external rotation plate 525 includes a plate-like body
526 having a front surface 527 a back surface 528, an anterior edge
529, a posterior edge 530, and side surfaces 531, 532. A drill
slide bushing 533 is connected to, and projects from, one side 532
of the external rotation plate 525. The drill slide bushing 533
includes a "D"-shaped bore 534 having a longitudinal axis parallel
to the front surface 527. A through hole in the side of the drill
slide bushing 533 threadably receives a set screw 524 in
communication with the flat side of the "D"-shaped bore. Three,
alignment holes 535 extend through the external rotation plate 525
from the front surface 527 to the back surface 528. A pivot pin
hole 536 extends through the external rotation plate 525 from the
front surface 527 to the back surface 528.
[0062] The external rotation plate 525 is mounted on the A/P sizer
base 502 with the external rotation plate front surface 527 flat
against the sizer base back surface 505. A pin 537 secured in the
pivot pin holes 517, 536 holds the assembly together and permits
planar rotation of the external rotation plate 525 relative to the
sizer base 502. The alignment holes 516, 535 are positioned so that
a pair of holes aligns when the external rotation plate 525 is
rotated relative to the sizer base 502 at each of 3.degree.,
5.degree., and 7.degree. as measured between a line perpendicular
to the top surfaces 512, 513 of the posterior condyle referencing
feet 510, 511 and the drill slide bushing 533 axis.
[0063] A femoral A/P sizing tower 540 includes a shaft 541 having a
first end 542, a second end 543, and a longitudinal axis extending
from the first end to the second end. A collar 544, connected to
the second end 543 of the sizing tower 540, includes a through hole
545 having an axis perpendicular to the longitudinal axis of the
shaft 541. A keyway 546 is cut in the side of the collar 544
opposite the shaft 541. Femoral A/P size indicia 547 are inscribed
on the shaft 541. The sizing tower 540 is mounted on the A/P sizer
base 502 with its shaft 541 slidably received within the tower
bushing 519 in coaxial relation such that the sizing tower 540 is
free to slide up and down, and rotate about, their coincident axes.
An anterior boom 550 includes a handle 551 and a shaft 552 having a
common longitudinal axis. A probe 553 extends beyond the shaft 552
and bends away from the shaft axis to a probe tip 554 that is
offset a predetermined distance from the shaft 552 axis. A key 555
extends longitudinally from the handle 551 and overlies a portion
of the shaft 552. The anterior boom 550 is mounted in the collar
544 of the sizing tower 540. The diameter of the probe 553 is
smaller than the keyway 546 and the diameter of the shaft 552 fits
closely with the through hole 545. Thus, the anterior boom 550 can
be mounted by moving the probe 554 down through the keyway 546 and
then sliding the shaft 552 into of the through hole 545. As the
shaft 552 is slid into place, the key 555 engages the keyway 546 to
prevent the anterior boom 550 from rotating about its shaft 552
axis. The handle 551 abuts the collar 544 to prevent the anterior
boom 550 from further translating along its shaft axis. Thus
mounted, the probe tip 554 is in a predetermined position relative
to the indicia 547 of the sizing tower 540. As the sizing tower 540
is moved up and down in the tower bushing 519, the probe tip 554
moves up and down in known relation to the top surfaces 512, 513 of
the posterior condyle referencing feet 510, 511. This relationship
is indicated by the position of the indicia 547 adjacent the top
surface 521 of the tower bushing 519. The sizing tower 540 can be
locked in position within the tower bushing bore 520 by tightening
the set screw 522.
[0064] A drill guide slide 560 includes a base 561 having a
dovetail profile 562 defining a longitudinal dovetail axis. A
support arm 563 extends from the base 561 perpendicular to the
dovetail and the dovetail axis. The support arm 563 is "D"-shaped,
being generally cylindrical with one side milled flat 564. The
support arm 563 is received in the bore 534 of the drill slide
bushing 533 for sliding movement along the bore axis. The "D"-shape
of the arm 563 and bore 534 prevents the arm from rotating. The
support arm 563 can be locked axially within the bore 534 by
tightening the set screw 524 so that it bears against the flat
564.
[0065] A parallel pin drill guide 570 includes a body 571 having
top 572, bottom 573, front 574, back 575, and side 576, 577
surfaces. A dovetail groove 592, having a longitudinal dovetail
groove axis, is formed from side-to-side in the bottom surface 573.
Drill guide holes 593 extend through the body 571 from
side-to-side. The guide holes 593 each have a longitudinal axis
that is parallel to the other and parallel to the longitudinal axis
of the dovetail groove 592. An anterior alignment hole 578 extends
through the body 571 from side-to-side to receive an alignment pin
579. The parallel pin drill guide 570 is mounted on the drill guide
slide 560 with the base dovetail 562 engaging, and coaxially
aligned with, the dovetail groove 592 so that the parallel pin
drill guide 570 can slide along the coincident axes. Thus
assembled, the guide hole 593 axes are parallel to the front
surface 504 of the A/P sizer base and they are at an angle relative
to the top surfaces 512, 513 of the posterior condyle referencing
feet 510, 511 as determined by the rotated position of the external
rotation plate 525. The alignment pin 579 can be extended over the
shaft 552 of the anterior boom 550 to act as a feeler gauge to
reference the vertical position of the drill guide 570 to the
vertical position of the probe tip 554. By adjusting the parallel
pin drill guide up and down until the alignment pin 579 rests on
the shaft 552, the guide holes 593 can be positioned at a
predetermined position relative to the probe tip 554. In this
illustrative embodiment, the A/P sizer base 502 and the external
rotation plate 525 are hinged on the lateral side in order to
adjust external rotation. Also in this illustrative embodiment,
only one drill slide bushing 533 (medial or lateral) is provided on
each external rotation plate 525. Because of this design, four A/P
sizer base 502 and external rotation plate 525 combinations would
be provided to allow for medial and lateral approaches to both a
left and a right knee.
[0066] In use, the handle 515 is assembled to the appropriate A/P
sizer 500 depending on whether the operative knee is left or right
and whether the approach is medial or lateral. In the illustrative
embodiment, the A/P sizer 500 is placed so that the front surface
504 of the A/P sizer base is flat against the resected distal femur
585 and the top surfaces 512, 513 of the feet 510, 511 are flush
against the posterior condyles 586, 587. Alternatively, the A/P
sizer could be placed on an unresected femur and the distal femoral
cut made later. In such a case, the distal cut depth could also be
set with the A/P sizer. The A/P sizer 500 offers three methods for
setting external rotation: the epicondylar axis, the A/P axis, or
the posterocondylar axis. To use the epicondylar axis, a line is
drawn between the medial and lateral epicondyles 588, 589. The feet
510,511 are placed against the posterior condyles 586, 587 and the
anterior edge 529 of the external rotation plate 525 is then set
parallel to the line drawn between the epicondyles 588, 589. The
pair of alignment holes 516, 535 that most nearly align are then
aligned and the sizer 500 is secured by inserting a spring pin 590
through the aligned holes 516, 535. Likewise, to use the A/P axis,
Whiteside's line is drawn along the A/P axis. The feet 510,511 are
placed against the posterior condyles 586, 587 and the anterior
edge 529 of the external rotation plate 525 is then set
perpendicular to the line drawn along the A/P axis. The pair of
alignment holes 516, 535 that most nearly align are then aligned
and the sizer 500 is secured by inserting a spring pin 590 through
the aligned holes 516, 535. To use the posterior condylar axis, the
appropriate set of alignment holes 516, 535 are aligned to
correspond to 3.degree., 5.degree., or 7.degree. of external
rotation while the feet 510, 511 are kept against the posterior
condyles 586, 587 and a spring pin 590 is inserted through the
aligned holes.
[0067] Once rotation is established, the A/P sizing tower 540 is
inserted into the tower bushing 519. The anterior boom 550 is
inserted into the collar 544 with the key 555 engaging the keyway
546. The probe tip 554 is positioned on the anterior cortex 591 of
the femur. The position of the probe tip 554 will determine the
exit point of the anterior bone cut and the ultimate position of
the femoral joint component. The vertical position of the A/P
sizing tower 540 is locked by tightening the set screw 522. The
femoral size is indicated by the indicia 547 appearing above the
top surface 521 of the tower bushing 519. The drill guide slide 560
is mounted in the drill slide bushing 533 and the parallel pin
drill guide 570 is mounted on the drill guide slide 560. The
alignment pin 579 is inserted through the anterior alignment hole
578. The drill guide 570 and drill guide slide 560 are raised until
the alignment pin 579 rests on top of the shaft 552 to set the A/P
position of the femoral component. The vertical position of the
drill guide slide 560 is locked by tightening the set screw 524.
The drill guide 570 is slid along the drill guide slide 560 until
it is adjacent the femur. A hole is drilled into the femur through
one of the guide holes 593 and a headless pin 594 is placed in the
drilled hole to establish a datum that records the rotation angle
and A/P position in such a way that the datum can be subsequently
referenced by bone cutting guides to produce bone cuts relative to
the rotation and position information. The illustrative embodiment
describes using pins set in the femur as datums. Other datums that
can record the information are contemplated and include by way of
example: one or more holes, screws, notches, and grooves. A single
pin can record the external rotation and A/P position. However,
rotation about the pin axis is not constrained by a single pin
without some other reference such as the distal femur. If desired,
a second hole can be drilled into the femur through the other guide
hole 593 and a second headless pin 595 placed to constrain rotation
about the pin axes and also to provide a more stable datum. All
components of the A/P sizer assembly 500 are now removed leaving
the headless pins 594, 595 in place to locate the femoral profile
cut.
[0068] The femoral box cuts, or profile, are cut using a femoral
profile cut block. FIGS. 30-32 show an illustrative femoral profile
cut block 600 for guiding the anterior, posterior and chamfer cuts
on the distal femur. The cut block 600 is generally an "L"-shaped
body having inner 602 and outer 604 distal surfaces, inner 606 and
outer 608 side surfaces, an anterior surface 610, and a posterior
surface 612. A pair of pin reference holes 614 extends through the
side of the cut block 600 from the outer side surface 608 to the
inner side surface 606 for receiving the headless femoral reference
pins 594, 595. The reference holes 614 are elongated
proximal-to-distal to allow proximal-to-distal motion relative to a
reference pin while still constraining the A/P position and
external rotation relative to the pin. This arrangement allows the
proximal-to-distal position of the block 600 to be referenced from
the distal surface 602 rather than the holes 614. A side fixation
hole 616 extends through the side of the cut block 600 from the
outer side surface 608 to the inner side surface 606 for receiving
a fixation pin. A distal fixation hole 618 extends through the
distal side of the cut block 600 front the outer distal surface 604
to the inner distal surface 602 for receiving a fixation pin.
Anterior 620, anterior chamfer 622, posterior 624, and posterior
chamfer 626 saw guide slots corresponding to the anterior,
posterior, and chamfer surfaces of a femoral implant box are
positioned in fixed predetermined relationship to the pin reference
holes 614. The slots sweep around the cut block 600 from the side
surfaces to the distal surfaces to permit a saw blade to be
directed medial-laterally and proximal-distally to make a complete
cut across the femur through each slot. A visualization window 628
extends from the outer distal surface 604 to the inner distal
surface 602 to allow direct visualization of the distal femur
during positioning of the cut block 600 and cutting of the distal
femur. When surgery is performed through a small surgical incision,
this window 628 permits the surgeon to observe the saw blade in
action. The medial side of the instrument is contoured to match the
incision by providing a notch 629 to provide soft tissue clearance
for the illustrative minimally invasive surgical procedure. For a
lateral approach, a cut block is provided with the lateral side
contoured to match the incision.
[0069] In use, the appropriate size femoral profile cut block 600
is positioned over the headless pins 594, 595 with the pins
engaging pin reference holes 614 which sets the A/P position and
external rotation of the cut block 600. The cut block 600 is
secured to the femur with a spring pin 630 through the distal
fixation hole 618. As the pin 630 is tightened, the cut block 600
can move proximally due to the elongated holes 614 until the inner
distal surface 602 is stably seated on the distal femur. An
additional spring pin 632 can be inserted from the side through the
side fixation hole 616 to further stabilize the cut block 600. A
saw blade can now be used to cut the femoral profile by directing
it through the posterior 624, posterior chamfer 626, anterior 620,
and anterior chamfer 622 saw guide slots. The cuts can be made in
any order; however, by making them in this order optimal stability
of the cut guide can be maintained. After the cuts are made, the
cut block and headless pins are removed.
[0070] Where required, a trochlear recess or notch is cut using a
trochlear notch guide. This would be required when a femoral
implant has a trochlear recess or notch that extends into the
anterodistal portion of the femoral box profile. For example, in an
implant where a deeper patellar groove is incorporated, extra
material may be added to the inside of the implant to accommodate
the deeper groove. Consequently, a cutout must be formed on the
bone to receive this extra material for a conforming fit between
the implant and bone. FIG. 33 shows an illustrative embodiment of a
trochlear cut guide 800. The trochlear cut guide 800 comprises a
generally "L"-shaped body including an anterior portion 802 having
an external anterior surface 804, an internal anterior surface 806,
opposing sides 808, 810, a proximal side 812, and a distal side
813. An anterior chisel guide slot 814 extends through the anterior
portion 802 from the external anterior surface 804 to the internal
anterior surface 806. The chisel guide slot 814 comprises a
proximal slot opening 816 and two side slot openings 818, 820. A
distal guide portion 830 extends at an angle from the distal side
813 of the anterior portion 802. The distal portion 830 includes an
external distal surface 832, an internal distal surface 834,
opposing sides 836, 838, a posterior side 840, and an anterior side
841. The anterior side 841 of the distal portion 830 and the distal
side 813 of the anterior portion 802 blend at a radius 815 to form
the connection between these two portions. A distal chisel guide
slot 842 extends through the distal portion 830 from the external
distal surface 832 to the internal distal surface 834. The chisel
guide slot 842 comprises a posterior slot opening 844 and two side
slot openings 846, 848. Ears 850 extend from each side 836, 838 of
the distal portion 830. The ears 850 include fixation holes 852 and
854. Distal drill guide holes 856 guide a drill for making peg
receiving holes in the distal femur. The chisel guide slots 814,
842 are aligned with the proximal slot opening 816 being coplanar
with the posterior slot opening 844 and the anterior portion side
slot openings 818, 820 being coplanar with the distal portion side
slot openings 846, 848. A cutting instrument inserted into distal
chisel guide slot 842 will exit anterior chisel guide slot 814 and
cut a notch across the anterodistal aspect of the femur.
[0071] FIG. 34 shows an alternative embodiment of a trochlear cut
guide comprising a slotted femoral provisional 860. This trochlear
cut guide facilitates making the trochlear notch cut and drilling
the distal peg holes in similar fashion as trochlear cut guide 800.
However, the slotted provisional 860 includes an external
articulating surface that matches the external articulating surface
of a corresponding femoral implant. This pennits the option of
finishing the tibial and patellar cuts and conducting a trial
reduction in which provisional implants of all of the knee
components are inserted and flexed through their range of motion to
check implant sizing and function. The mediolateral position of the
slotted femoral provisional 860 can be adjusted and retested before
making the trochlear notch cut and drilling the distal peg holes
which set the mediolateral position. The slotted provisional 860
articular surfaces include an anterior patellar flange 864
connecting arcuate, spaced apart distal 865, 866 and posterior 867,
868 condyles. Opposite the articulating surfaces are the internal
box surfaces including anterior 870, anterior chamfer 871, distal
872, posterior chamfer 873, and posterior 874 box surfaces. An
anterior chisel guide slot 875 extends through the anterior flange
864 from the external anterior surface to the internal anterior box
surface 870. The chisel guide slot 875 comprises a proximal slot
opening 876 and two side slot openings 877, 878. A distal chisel
guide slot 879 extends through the distal condyles 865, 866 from
the external distal surface to the internal distal box surface 872.
The distal chisel guide slot 879 comprises a posterior slot opening
880 and two side slot openings 881, 882. Distal drill guide holes
883 guide a drill for making peg receiving holes in the distal
femur. Anterior chisel guide slot 875, distal chisel guide slot
879, and drill guide holes 883 are configured and function like
those of the trochlear cut guide 800 of FIG. 33.
[0072] The use of the trochlear notch cutting guide will be
described with reference to the slotted provisional embodiment 860
of FIG. 34. The appropriate size femoral provisional is placed on
the end of the femur 884. The appropriate mediolateral position can
be established visually or, in the case of the slotted provisional
860, by trial reduction. A hole is drilled into the distal femur
through one of the drill guide holes 883 and a holding peg (not
shown) is inserted. A hole is drilled into the femur through the
other one of the drill guide holes 883 and another holding peg is
inserted. A chisel 885 having a three sided blade configured to
engage the chisel guide slots 875, 879 is inserted into the distal
chisel guide slot 879. The chisel 885 is driven across the distal
femur to engage the anterior chisel guide slot 875 and cut the
trochlear notch.
[0073] Posterior stabilized femoral components have a protruding
cam box. A piece of bone is cut from the intercondylar region of
the distal femur using an intercondylar notch guide to accommodate
this cam box. FIGS. 35-36 show an illustrative embodiment of an
intercondylar notch guide 900. The notch guide 900 comprises a
generally "L"-shaped body including an anterior portion 901 having
an anterior outer surface 902 and an anterior inner surface 904.
Spaced apart condylar portions 906, 908 depend at an angle from the
anterior portion 901 to define a "U"-shaped opening 907 between
them. The condylar portions have distal inner 910 and outer 912
surfaces. A trochlear ramp 914 projects from the anterior inner
surface 904. The ramp 914 has a planar, distal saw guide surface
916 that intersects the anterior outer surface 902 and defines the
closed end of the "U"-shaped opening 907. The condylar portions
906, 908 have parallel, spaced apart, inner side walls 918, 920.
The side walls 918, 920 define medial and lateral saw guide
surfaces perpendicular to distal saw guide surface 916. Each of the
condylar portions 906, 908 includes a threaded peg hole 922, 924.
Pegs can optionally be threaded into the holes to extend from the
distal inner surface 910. In use, the appropriate size
intercondylar notch guide 900 is chosen and placed on the distal
femur. The trochlear ramp 914 fits within the trochlear notch cut
in the prior step to position the notch guide mediolaterally.
Additionally, pegs can be threaded into peg holes 922, 924 to align
mediolaterally with the femoral peg holes drilled in the prior
step. A saw blade is then guided along the distal 916 and side 918,
920 saw guiding surfaces to cut the base and sides of the
intercondylar notch. The cut bone and intercondylar notch guide are
then removed.
[0074] It will be understood by those skilled in the art that the
foregoing has described illustrative embodiments of the present
invention and that variations may be made to these embodiments
without departing from the spirit and scope of the invention
defined by the appended claims. For example the illustrative
embodiments depict using saw guides and blades to make the bone
cuts. However, the claimed methods and alignment guides could also
be used with other bone removal systems to set their reference
bases to achieve the desired position and rotation of prepared bone
surfaces.
* * * * *