U.S. patent application number 12/609666 was filed with the patent office on 2010-08-05 for force sensing distal femoral alignment system and method of use.
This patent application is currently assigned to Synvavise Technology, Inc.. Invention is credited to Leo Beckers, Barjinder Singh Chana, Michael G. Fisher, Michael Haight.
Application Number | 20100198275 12/609666 |
Document ID | / |
Family ID | 42129308 |
Filed Date | 2010-08-05 |
United States Patent
Application |
20100198275 |
Kind Code |
A1 |
Chana; Barjinder Singh ; et
al. |
August 5, 2010 |
FORCE SENSING DISTAL FEMORAL ALIGNMENT SYSTEM AND METHOD OF USE
Abstract
Devices, systems, and methods are provided for facilitating the
aligning and balancing of the knee during total knee replacement
surgery. A femoral assembly is engaged with a distal femur. The
positions of medial and lateral portions of the femoral assembly
relative to a stationary portion of the femoral assembly can be
separately adjusted to adjust the alignment of the knee. A force
sensor will be provided to sense the forces in the medial and
lateral portions of the knee, and the medial and lateral portions
of the femoral assemblies will be adjusted so that the sensed
forces are balanced. The alignment of the knee is visually verified
using a knee alignment verification member coupled to the femoral
assembly. The knee alignment verification member may emit laser
beams along the mechanical axes of the femur and tibia, or the knee
alignment verification member may couple to alignment rods aligned
along these axes.
Inventors: |
Chana; Barjinder Singh;
(Rancho Cordova, CA) ; Fisher; Michael G.;
(Folsom, CA) ; Haight; Michael; (Sacramento,
CA) ; Beckers; Leo; (Grimbergen, BE) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER, EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
Synvavise Technology, Inc.
El Dorado Hills
CA
|
Family ID: |
42129308 |
Appl. No.: |
12/609666 |
Filed: |
October 30, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61109770 |
Oct 30, 2008 |
|
|
|
Current U.S.
Class: |
606/86R ;
600/587 |
Current CPC
Class: |
A61B 17/025 20130101;
A61B 2017/0268 20130101; A61B 2090/064 20160201; A61B 17/155
20130101 |
Class at
Publication: |
606/86.R ;
600/587 |
International
Class: |
A61B 17/56 20060101
A61B017/56; A61B 5/103 20060101 A61B005/103 |
Claims
1. A system for aligning the knee during a surgical procedure on
the knee, the system comprising: a femoral assembly removably
engagable with a distal femur, the femoral assembly including a
stationary femoral portion, an adjustable medial femoral portion
coupled to the stationary femoral portion, and an adjustable
lateral femoral portion coupled to the stationary femoral portion;
a knee alignment verification member coupleable with the stationary
femoral portion of the femoral assembly and providing visual
confirmation of a femoral and tibial mechanical axes of the knee;
and a force sensor coupleable with the stationary femoral portion
of the femoral assembly, the force sensor comprising a medial
portion for sensing a first force in a medial portion of the knee
and a lateral portion for sensing a second force in a lateral
portion of the knee.
2. The system of claim 1, wherein the knee alignment verification
member means includes a laser knee alignment verification member
coupleable to the stationary femoral portion and providing a first
laser beam oriented along the femoral axis of the knee and a second
laser beam oriented along the tibial axis of the knee.
3. The system of claim 1, wherein the knee alignment verification
member includes a mechanical knee alignment verification assembly,
the mechanical knee alignment verification assembly comprising: a
knee alignment hub; a first rod coupleable with the knee alignment
hub to be oriented along the femoral axis of the knee; and a second
rod coupleable with the knee alignment hub to be oriented along the
tibial axis of the knee.
4. The system of claim 1, wherein the adjustable medial portion
comprises a medial paddle, and the adjustable femoral portion
comprises a lateral paddle.
5. The system of claim 1, wherein the position of the adjustable
medial femoral portion relative to the stationary femoral portion
is adjustable, and the position of the adjustable lateral femoral
portion relative to the stationary femoral portion is
adjustable.
6. The system of claim 5, wherein the adjustable medial femoral
portion and the adjustable lateral femoral portion are separately
adjustable.
7. The system of claim 5, wherein a medial rotatable screw couples
the adjustable medial femoral portion with the stationary femoral
portion, and a lateral rotatable screw couples the adjustable
lateral femoral portion with the stationary femoral portion.
8. The system of claim 7, wherein rotating the medial rotatable
screw adjusts the position of the adjustable medial femoral portion
relative to the stationary femoral portion, and rotating the
lateral rotatable screw adjusts the position of the adjustable
lateral femoral portion relative to the stationary femoral
portion.
9. The system of claim 1, wherein the force sensor comprises a
force sensing element selected from the group consisting of
piezoelectric sensors, force sensing resistors, force sensing
capacitors, strain gages, load cells, and pressure sensors.
10. The system of claim 1, further comprising: a processor coupled
with the force sensor for processing sensed force data into usable
data for providing to a user; and a visual display coupled with the
processor and adapted to display the usable data.
11. The system of claim 10, wherein the visual display displays
usable data representing a first force sensed in the medial portion
of the knee and a second force sensed in the lateral portion of the
knee.
12. The system of claim 1, further comprising a plurality of
locating pins, and wherein the stationary femoral portion defines
at least one medial aperture for positioning a first at least
locating pin on the distal femur and at least one lateral aperture
for positioning a second at least one locating pin on the distal
femur.
13. The system of claim 12, further comprising a cutting guide
removably engagable with the distal femur, the cutting guide being
positioned relative to the distal femur based on the position of at
least one first locating pin and the at least one second locating
pin.
14. The system of claim 1, wherein the force sensor is removably
coupleable to a thickness adapter, the adapter configured to fill
the space between the femur and tibia.
15. The system of claim 1, wherein the adjustable medial femoral
portion and the adjustable lateral femoral portion include a medial
fulcrum and lateral fulcrum, the fulcrums positionable against the
provisionally cut distal femur when the distal femoral alignment
assembly is mounted against the distal femur.
16. The system of claim 15, wherein a bone interface plate is
disposed between the fulcrums and the distal femur.
17. A method for aligning the knee during a surgical procedure on
the knee, the method comprising: engaging a femoral assembly with a
distal femur, the femoral assembly including a stationary femoral
portion, an adjustable medial femoral portion coupled to the
stationary femoral portion, and an adjustable lateral femoral
portion coupled to the stationary femoral portion; coupling a force
sensor with the stationary femoral portion of the femoral assembly;
sensing a first force in a medial portion of the knee and a second
force in the lateral portion of the knee using the coupled force
sensor; separately adjusting the position of the adjustable medial
femoral portion relative to the stationary femoral portion and the
position of the adjustable lateral femoral portion relative to the
stationary femoral portion based on the sensed first and second
forces to align a femoral and tibial mechanical axes of the knee;
and visually confirming the alignment of the femoral and tibial
mechanical axes of the knee using a knee alignment verification
assembly coupleable with the stationary femoral portion of the
femoral assembly.
18. The method of claim 17, further comprising: coupling a
mechanical knee alignment verification assembly with the stationary
femoral member of the femoral assembly; aligning a first alignment
rod of the mechanical knee alignment verification assembly along
the femoral axis of the knee; and aligning a second alignment rod
of the mechanical knee alignment verification assembly along the
tibial axis of the knee, wherein visually confirming the alignment
of the femoral and tibial mechanical axes of the knee comprises
visually confirming the alignment of the first alignment rod and
the second alignment rod relative to each other.
19. The method of claim 17, further comprising: coupling a laser
knee alignment verification member with the stationary femoral
member of the femoral assembly; aligning a first laser beam from
the laser knee alignment verification member along the femoral
mechanical axis of the knee; and aligning a second laser beam from
the laser knee alignment verification member along the tibial
mechanical axis of the knee along the tibial axis of the knee,
wherein visually confirming the alignment of the femoral and tibial
mechanical axes of the knee comprises visually confirming the
alignment of the first laser beam and the alignment of the second
laser beam relative to each other.
20. The method of claim 17, wherein the positions of the adjustable
medial femoral portion relative to the stationary femoral portion
and of the adjustable lateral femoral portion relative to the
stationary femoral portion are adjusted based on the sensed first
force and the sensed second force so that the first and second
forces are balanced.
21. The method of claim 17, wherein sensing a first force in a
medial portion of the knee and a second force in a lateral portion
of the knee using the coupled force sensor comprises: transmitting
a voltage to a sensor element of a thin force sensing portion of
the force sensor; measuring the voltage after it has passed through
the sensor element; determining a percentage of the voltage passed
through the sensor element relative to the voltage transmitted to
the sensor element; and deriving the measured force from the
percentage.
22. The method of claim 17, further comprising displaying the
sensed first force and the sensed second force with a visual
display coupled to the force sensor.
23. The method of claim 17, where separately adjusting the position
of the adjustable medial femoral portion relative to the stationary
femoral portion and the position of the adjustable lateral femoral
portion relative to the stationary femoral portion comprises
rotating at least one of a lateral rotatable screw coupling the
adjustable lateral femoral portion to the stationary femoral
portion and a medial rotatable screw coupling the adjustable medial
femoral portion to the stationary femoral portion.
24. The method of claim 17, wherein the stationary femoral portion
defines at least one medial aperture and at least one lateral
aperture, the method further comprising positioning a first at
least one locating pin on the distal femur based on the at least
one medial aperture and positioning a second at least one locating
pin on the distal femur based on the at least one lateral
aperture.
25. The method of claim 24, further comprising disengaging the
femoral assembly with the distal femur and engaging a distal
femoral cutting guide with the distal femur, the distal femoral
cutting guide being positioned relative to the distal femur based
on the positioned first and second at least one locating pins.
26. The method of claim 25, further comprising making cuts on the
distal femur based on the position of the distal femoral cutting
guide.
27. A method for aligning a leg having a femur and a tibia during
knee surgery, the femur having a mechanical axis, a distal end and
a proximal end and the tibia having a mechanical axis, a distal end
and a proximal end, the method comprising: engaging a femoral
assembly with the provisionally cut distal end of the femur, the
femoral assembly including a stationary femoral portion, an
adjustable medial femoral portion having a medial pivot fulcrum
coupled to the stationary femoral portion, and an adjustable
lateral femoral portion having a lateral pivot fulcrum coupled to
the stationary femoral portion; coupling a force sensor with the
stationary femoral portion of the femoral assembly; reversibly
coupling a medial posterior member to the medial side of the
stationary femoral portion; reversibly coupling a lateral posterior
member to the lateral side of the stationary femoral portion;
abutting the medial member against the medial posterior femur;
abutting the lateral member against the lateral posterior femur;
sensing a first force in a medial portion of the knee and a second
force in the lateral portion of the knee using the coupled force
sensor; separately adjusting the position of the adjustable medial
femoral portion relative to the stationary femoral portion and the
position of the adjustable lateral femoral portion relative to the
stationary femoral portion based on the sensed first and second
forces to align the femoral and tibial mechanical axes of the knee;
and visually confirming the alignment of the femoral and tibial
mechanical axes of the knee using a knee alignment verification
assembly coupleable with the stationary femoral portion of the
femoral assembly.
28. The method of claim 27, wherein the abutting occurs with the
leg in full extension.
29. The method of claim 27, wherein the medial and lateral fulcrums
determine fixed distance points to adjust an angle.
30. The method of claim 27, wherein a bone interface plate is
disposed between the adjustable medial and lateral femoral portions
and the distal femur.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a non-provisional of, and claims
the benefit of priority under 35 U.S.C. .sctn.119(e), U.S.
Provisional Application No. 61/109,770 (Attorney Docket No.
021976-000900US) filed Oct. 30, 2008, the entire contents of which
are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of Invention
[0003] The present invention relates generally to medical surgical
devices, systems, and methods. More specifically, the invention
relates to devices, systems and methods for facilitating knee
surgery procedures, in particular, knee replacement procedures.
[0004] The knee is generally defined as the point of articulation
of the femur with the tibia. Structures that make up the knee
include the distal femur, the proximal tibia, the patella, and the
soft tissues within and surrounding the knee joint, the soft
tissues including the ligaments of the knee. The knee is generally
divided into three compartments: medial (the inside part of the
knee), lateral (the outside part of the knee), and patello-femoral
(the joint between the kneecap and the femur). The medial
compartment comprises the medial joint surfaces of the femur,
tibia, and the meniscus wedged therebetween. The lateral
compartment comprises the lateral joint surfaces of the femur,
tibia, and the meniscus wedged therebetween. The patellofemoral
compartment comprises the joint between the undersurface of the
kneecap or patella and the femur. Four ligaments are especially
important in the stability, alignment and functioning of the
knee--the anterior cruciate ligament, the posterior cruciate
ligament, the medial collateral ligament, and the lateral
collateral ligament. In an arthritic knee, protective cartilage at
the point of articulation of the femur with the tibia is often worn
away, allowing the femur to directly contact the tibia. This
bone-on-bone contact can cause significant pain, discomfort, and
disability for a patient and will often necessitate knee
replacement or knee arthroplasty.
[0005] Knee arthroplasty involves replacing the diseased and
painful joint surface of the knee with metal and plastic components
shaped to allow natural motion of the knee. Knee replacement may be
total or partial. Total knee replacement surgery, also referred to
as total knee arthroplasty ("TKA"), involves a total replacement of
the distal end of the femur, the proximal end of the tibia, and
often the inner surface of the patella with prosthetic parts. Cuts
are made on the distal end of the femur and the proximal end of the
tibia. Prosthetic parts are then attached. The prosthetic parts
create a stable knee joint that moves through a wide range of
motion. The replacement of knee structures with prosthetic parts
allows the knee to avoid bone-on-bone contact and provides smooth,
well-aligned surfaces for joint movement.
[0006] In knee replacement surgeries, it is often vital to restore
the mechanical alignment of the knee, i.e., the proper alignment of
the mechanical axes of the femur and tibia with each other. Many
methods and devices currently are used to restore the mechanical
alignment of the leg. These methods and devices are typically used
during Total Knee Replacement surgery and include alignment rods,
e.g., intramedullary and extramedullary rods, surgical navigation
systems, and CT and or MRI based "bone morphing" or `shape-fitting"
technologies. Generally, empirical anatomical landmarks are used in
these methods. These anatomical landmarks are either
directly/mechanically observed intra-operatively, or indirectly
relied upon, serving as the foundation of a computer generated
reference method. Reference geometry and physical or virtual
measurements are often used to ultimately align bone-cutting guides
or templates which facilitate bone resections (made with a surgical
saw blade). These bone resections will typically properly orient a
knee prosthesis in the correct location/alignment. Generally, none
of these methods directly take the condition or tendencies of the
soft-tissue structures, such as the lateral collateral and medial
collateral ligaments, about the knee into consideration.
[0007] Historically, surgeons performing total knee replacement
surgery in the late 1970s and early 1980s, would typically first
resect the proximal tibia, creating a flat surface perpendicular to
the shaft of the tibia. The leg was then brought to extension.
Spacer blocks were shoved between the resected tibia and the uncut
distal femur. The spacer blocks were selected from various
thicknesses in order to distract the knee joint space to the extent
the ligaments about the knee were somewhat taut. Once the knee
joint was distracted to that taut condition, a distal femoral
cutting guide was positioned in a way to yield a distal femoral
bone cut parallel to the tibial cut. It was believed then, a distal
femoral bone cut using this method of distracting the joint space
between the tibia and femur, would yield proper alignment of the
mechanical axis of the leg. This method would often prove
successful as practiced by a skilled surgeon and in the case of
"passive deformities" of the knee. However, the distraction method
would typically not have any accurate means of determining ligament
forces between the medial side of the knee and/or the lateral side
of the knee. As such, proper alignment would often not be restored.
Additionally, the method of first making a proximal tibial bone
resection and then making a distal femoral bone resection parallel
to the tibial bone resection did not restore proper alignment of
the leg in the case of "fixed deformities" of the knee. The case of
"fixed deformities" of the knee would otherwise require ligament
releases to restore proper alignment of the knee. Accordingly, many
early knee replacement surgeons determined the tibial bone
resection and the distal femoral bone resections should be made
independent of each other.
[0008] As technology has advanced, including the introduction of CT
scanners and MRI technology, the thought of computerized bone
morphing has gained popularity as a means to accurately place
cutting guides. The cutting guides in turn would be used in efforts
to place prosthetic knee implants in a position in which the knee
is properly aligned. Early studies have not found these bone
morphing technologies always accurate, reporting proper alignment
of the leg was not restored. However, a proper patient selection,
e.g., patients with mild, passive deformities of the knee, might be
viable candidates for bone morphing technology, assuming those
patients/deformities could be properly corrected by simple
anatomical referencing, as determined by a CT or MRI scan.
[0009] However, bone morphing technology is often costly, requiring
a CT or MRI scan to determine any given patient's anatomy.
Electronic images from such scans must be "filtered" by a computer
technician. The "filtered" scan data must be electronically
conveyed to some type of fabrication machine, such as a CNC
Machining Center or a Rapid Prototype Machine. Ultimately,
"shape-matching" and "patient specific" cutting guides must be
produced and delivered into surgery.
[0010] As such, there is a clear need for systems, devices, and
methods of knee surgery that can help surgeons quickly, accurately,
and cost-effectively position the distal femoral cutting guide,
thus restoring proper alignment and soft-tissue balance of the leg
during total knee replacement surgery.
[0011] 2. Description of Background Art
[0012] Non-patent literature which may be of interest may include:
Murray, David G., "Variable Axis.TM. Total Knee Surgical
Technique," Howmedica Surgical Techniques, Howmedica Inc. 1977;
Mihalko, W H et al., "Comparison of Ligament-Balancing Techniques
During Total Knee Arthroplasty," Jnl. Bone & Jt. Surg., Vol.
85-A Supplement 4, 2003, 132-135; Eckhoff, D G et al.,
''Three-Dimensional Morphology and Kinematics of the Distal Part of
the Femur Viewed in Virtual Reality, Jnl. Bone & Jt. Surg.,
Vol. 85-A Supplement 4, 2003, 97-104; and Ries, M D, et al.,
"Soft-Tissue Balance in Revision Total Knee Arthroplasty," Jnl.
Bone & Jt. Surg., Vol. 85-A Supplement 4, 2003, 38-42. Patents
of interest may include U.S. Pat. Nos. 4,501,266; 4,646,729;
4,703,751; 4,841,975; 5,116,338; 5,417,694; 5,540,696; 5,597,379;
5,720,752; 5,733,292; 5,800,438; 5,860,980; 5,911,723; 6,022,377
and 6,758,850. Patents applications of interest may include
co-assigned U.S. patent application Ser. Nos. 10/773,608, now U.S.
Pat. No. 7,442,196, entitled "Dynamic Knee Balancer" (Attorney
Docket No. 021976-000200US); 10/973,936, now U.S. Pat. No.
7,578,821 entitled "Dynamic Knee Balancer with Pressure Sensing"
(Attorney Docket No. 021976-000210US); 11/149,944 now U.S. Patent
Publication Application No. 2005/0267485 A1 entitled "Dynamic Knee
Balancer with Opposing Adjustment Mechanism" (Attorney Docket No.
021976-000220US); 61/090,535 entitled "Sensing Force During Partial
and Total Knee Replacement Surgery" (Attorney Docket No.
021976-000800US); and 61/107,973 entitled "Dynamic Knee Balancing
for Revision Procedures" (Attorney Docket No. 021976-000700US), the
entire contents of each of which are incorporated herein by
reference.
BRIEF SUMMARY OF THE INVENTION
[0013] The present invention provides devices, systems, and methods
for facilitating a surgery performed on a knee, particularly by
facilitating the aligning of the knee during a total knee
replacement surgery. A femoral assembly is engaged with a distal
femur and placed in the gap between the distal femur and proximal
tibia. The femoral assembly comprises a stationary portion, an
adjustable medial portion, and an adjustable lateral femoral
portion. The positions of the medial and lateral femoral portions
relative to the stationary portion can be separately adjusted to
adjust the varus-valgus alignment of the knee, e.g., the angle
between the femur and tibia, as well as the tension in the soft
tissues adjacent the knee. Additionally, the femoral assembly
comprises adjustable posterior members that fill the posterior
capsule of the knee with a thickness similar to the prosthetic
femoral implant. Typically, a force sensor will be provided to
sense the forces in the medial portion of the knee and the lateral
portion of the knee, and the medial and lateral femoral portions
will be adjusted so that the sensed forces are balanced. A visual
display may be provided to show the surgeon the sensed forces. In
addition, a thickness adapter may be provided to removable attach
to the force sensor to fill the space between the femur and tibia
to the point force readings are obtained. The alignment of the knee
can be visually verified using a knee alignment verification member
coupled to the femoral assembly, and further verified by angular
graduation markings placed upon the femoral stationary portion. The
knee alignment verification member may emit laser beams along the
mechanical axes of the femur and tibia. Or, alignment rods which
align along the mechanical axes of the femur and tibia may be
coupled to the knee alignment verification member. The alignment of
the knee can be verified using with the laser beams and/or the
alignment rods. When the knee is properly aligned, placement pins
may be positioned in the distal femur guided by the femoral
assembly. The femoral assembly can then be removed and a cutting
guide can be positioned on the distal femur based on the position
of the placement pins. A cut parallel to a previously made cut on
the tibia can then be made on the distal femur. A prosthetic knee
placed on these cuts will maintain the proper alignment of the
knee.
[0014] In a first aspect, the invention provides a system for
aligning the knee during a surgical procedure on the knee. The
system comprises a femoral assembly that is removably engaged with
a distal femur. The femoral assembly includes a stationary femoral
portion, an adjustable medial femoral portion (which is coupled to
the stationary femoral portion), and an adjustable lateral femoral
portion (which is coupled to the stationary femoral portion. A knee
alignment verification member is coupled with the stationary
femoral portion of the femoral assembly and provides visual
confirmation of a femoral and tibial mechanical axes of the knee. A
force sensor is coupled with the stationary femoral portion of the
femoral assembly. The force sensor comprises a medial portion for
sensing a first force in a medial portion of the knee and a lateral
portion for sensing a second force in a lateral portion of the
knee.
[0015] In one embodiment, the knee alignment verification member
means includes a laser knee alignment verification member is
coupled to the stationary femoral portion. The laser knee alignment
provides a first laser beam oriented along the femoral axis of the
knee and a second laser beam oriented along the tibial axis of the
knee.
[0016] In some embodiments, the knee alignment verification member
includes a mechanical knee alignment verification assembly. The
mechanical knee alignment verification assembly includes a knee
alignment hub. A first rod is coupled with the knee alignment hub
to be oriented along the femoral axis of the knee and a second rod
is coupled with the knee alignment hub to be oriented along the
tibial axis of the knee.
[0017] In an embodiment, the adjustable medial portion includes a
medial paddle and the adjustable femoral portion includes a lateral
paddle.
[0018] In still other embodiments, the position of the adjustable
medial femoral portion relative to the stationary femoral portion
is adjustable. The position of the adjustable lateral femoral
portion relative to the stationary femoral portion is
adjustable.
[0019] In other embodiments, the adjustable medial femoral portion
and the adjustable lateral femoral portion are separately
adjustable.
[0020] In some embodiments, a medial rotatable screw couples the
adjustable medial femoral portion with the stationary femoral
portion. A lateral rotatable screw couples the adjustable lateral
femoral portion with the stationary femoral portion.
[0021] In some embodiments, rotating the medial rotatable screw
adjusts the position of the adjustable medial femoral portion
relative to the stationary femoral portion. Rotating the lateral
rotatable screw adjusts the position of the adjustable lateral
femoral portion relative to the stationary femoral portion.
[0022] In some embodiments, the force sensor comprises a force
sensing element selected from the group consisting of piezoelectric
sensors, force sensing resistors, force sensing capacitors, strain
gages, load cells, and pressure sensors.
[0023] In still other embodiments, a processor is coupled with the
force sensor for processing sensed force data into usable data and
for providing the data to a user. A visual display is coupled with
the processor and adapted to display the usable data.
[0024] In some embodiments, the visual display displays usable data
representing a first force sensed in the medial portion of the knee
and a second force sensed in the lateral portion of the knee.
[0025] In some embodiments, the system for aligning a knee during
knee surgery includes a plurality of locating pins. The stationary
femoral portion defines at least one medial aperture for
positioning at least one locating pin on the distal femur and at
least one lateral aperture for positioning at least a second
locating pin on the distal femur.
[0026] In some embodiments of the invention, a cutting guide is
removably engaged with the distal femur. The cutting guide is
positioned relative to the distal femur based on the position of at
least one first locating pin and the at least a second locating
pin.
[0027] In some embodiments, the force sensor is removably coupled
to a thickness adapter. The adapter fills the space between the
femur and tibia.
[0028] In some embodiments, the adjustable medial femoral portion
and the adjustable lateral femoral portion include a medial fulcrum
and lateral fulcrum. The fulcrums are positioned against the
provisionally cut distal femur when the distal femoral alignment
assembly is mounted against the distal femur. In other embodiments,
a bone interface plate is disposed between the fulcrums and the
distal femur.
[0029] In a second aspect, the invention provides a method for
aligning the knee during a surgical procedure on the knee including
engaging a femoral assembly with a distal femur. The femoral
assembly includes a stationary femoral portion, an adjustable
medial femoral portion (coupled to the stationary femoral portion),
and an adjustable lateral femoral portion (coupled to the
stationary femoral portion). A force sensor is coupled with the
stationary femoral portion of the femoral assembly. A first force
is sensed in a medial portion of the knee and a second force is
sensed in the lateral portion of the knee using the coupled force
sensor. The position of the adjustable medial femoral portion can
be adjusted separately relative to the stationary femoral portion
and the position of the adjustable lateral femoral portion is
separately adjustable relative to the stationary femoral portion
based on the sensed first and second forces to align a femoral and
tibial mechanical axes of the knee. The alignment of the femoral
and tibial mechanical axes of the knee are visually confirmed using
a knee alignment verification assembly coupled with the stationary
femoral portion of the femoral assembly.
[0030] In one embodiment, a method for aligning the knee during a
surgical procedure on the knee comprises coupling a mechanical knee
alignment verification assembly with the stationary femoral member
of the femoral assembly. A first alignment rod of the mechanical
knee alignment verification assembly is aligned along the femoral
axis of the knee and a second alignment rod of the mechanical knee
alignment verification assembly is aligned along the tibial axis of
the knee. The femoral and tibial mechanical axes of the knee is
visually confirmed by the alignment of the first alignment rod and
the second alignment rod relative to each other.
[0031] In another embodiment, a laser knee alignment verification
member is coupled with the stationary femoral member of the femoral
assembly, A first laser beam from the laser knee alignment
verification member is aligned along the femoral mechanical axis of
the knee and a second laser beam from the laser knee alignment
verification member is aligned along the tibial mechanical axis of
the knee along the tibial axis of the knee, The alignment of the
femoral and tibial mechanical axes of the knee is visually
confirmed by the alignment of the first laser beam and the
alignment of the second laser beam relative to each other.
[0032] In some embodiments, the positions of the adjustable medial
femoral portion relative to the stationary femoral portion and of
the adjustable lateral femoral portion relative to the stationary
femoral portion are adjusted based on the sensed first force and
the sensed second force so that the first and second forces are
balanced.
[0033] In some embodiments, the first force in a medial portion of
the knee is sensed and a second force in a lateral portion of the
knee is sensed using the coupled force sensor. This includes
transmitting a voltage to a sensor element of a thin force sensing
portion of the force sensor and measuring the voltage after it has
passed through the sensor element. The percentage of the voltage
that passed through the sensor element is determined relative to
the voltage transmitted to the sensor element. The measured force
is derived from the percentage.
[0034] In yet another embodiment, the sensed first force and the
sensed second force is visually displayed by a display coupled to
the force sensor.
[0035] In some embodiments, separately adjusting the position of
the adjustable medial femoral portion relative to the stationary
femoral portion and the position of the adjustable lateral femoral
portion relative to the stationary femoral portion comprises
rotating at least one of a lateral rotatable screw coupling the
adjustable lateral femoral portion to the stationary femoral
portion and a medial rotatable screw coupling the adjustable medial
femoral portion to the stationary femoral portion.
[0036] In some embodiments, the stationary femoral portion defines
at least one medial aperture and at least one lateral aperture. The
method further includes positioning at least one locating pin on
the distal femur based on at least one medial aperture and
positioning at least a second locating pin on the distal femur
based on the at least one lateral aperture.
[0037] In an embodiment, the femoral assembly is disengaged with
the distal femur and engages a distal femoral cutting guide with
the distal femur. The distal femoral cutting guide is positioned
relative to the distal femur based on the position of at least one
first and at least one second locating pins.
[0038] In some embodiments, cuts are made on the distal femur based
on the position of the distal femoral cutting guide.
[0039] In another aspect, the invention provides a method for
aligning a leg during knee surgery. The leg has a femur and a
tibia. The femur has a mechanical axis, a distal end and a proximal
end. The tibia has a mechanical axis, a distal end and a proximal
end. The method of aligning the leg includes engaging a femoral
assembly with the provisionally cut distal end of the femur. The
femoral assembly includes a stationary femoral portion, an
adjustable medial femoral portion that has a medial pivot fulcrum
coupled to the stationary femoral portion, and an adjustable
lateral femoral portion that has a lateral pivot fulcrum coupled to
the stationary femoral portion. A force sensor is coupled with the
stationary femoral portion of the femoral assembly. A medial
posterior member is reversibly coupled to the medial side of the
stationary femoral portion. A lateral posterior member is
reversibly coupled to the lateral side of the stationary femoral
portion. The medial member abuts the medial posterior femur and the
lateral member abuts the lateral posterior femur. A first force is
sensed in a medial portion of the knee and a second force is sensed
in the lateral portion of the knee using the force sensor. The
position of the adjustable medial femoral portion is adjusted
relative to the stationary femoral portion and the position of the
adjustable lateral femoral portion is (separately) adjusted
relative to the stationary femoral portion based on the sensed
first and second forces to align the femoral and tibial mechanical
axes of the knee. The alignment of the femoral and tibial
mechanical axes of the knee is visually confirmed using a knee
alignment verification assembly which is coupled with the
stationary femoral portion of the femoral assembly.
[0040] In one embodiment, the medial member abuts the medial
posterior femur and the lateral member abuts the lateral posterior
femur when the leg is fully extended.
[0041] In some embodiments, the medial and lateral fulcrums
determine fixed distance points to adjust an angle.
[0042] In some embodiments, a bone interface plate is disposed
between the adjustable medial and lateral femoral portions and the
distal femur.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] FIG. 1 shows an exploded view of a distal femoral alignment
component assembly according to embodiments of the invention.
[0044] FIG. 2 shows a top view of the unadjusted distal femoral
alignment assembly of FIG. 1.
[0045] FIG. 3 shows a top view of the adjusted distal femoral
alignment assembly of FIG. 1.
[0046] FIG. 4 shows a perspective view of the unadjusted distal
femoral alignment assembly of FIG. 1.
[0047] FIG. 5 shows a perspective view of the adjusted distal
femoral alignment assembly of FIG. 1.
[0048] FIGS. 6 and 7 shows perspective views of a knee alignment
system according to embodiments of the invention.
[0049] FIG. 8 shows a visual display of a knee alignment system
according to embodiments of the invention.
[0050] FIGS. 9-10 show a side view of a knee alignment system,
including the distal femoral alignment component and the force
sensor coupled together, being placed in the gap.
[0051] FIGS. 11-12 show a perspective view of a knee alignment
system, including the distal femoral alignment component and the
force sensor coupled together, being placed in the gap.
[0052] FIGS. 13-23 show a method of aligning a knee during surgery
according to embodiments of the invention.
[0053] FIG. 24A-B shows exploded views of a knee alignment system
according to embodiments of the invention.
[0054] FIG. 25 shows a top view of the unadjusted distal femoral
alignment assembly.
[0055] FIGS. 26A and 26C show perspective posterior views of the
unadjusted distal femoral alignment assembly shown in FIG. 25.
[0056] FIG. 26B shows a posterior perspective of the unadjusted
distal femoral alignment assemblies shown in FIGS. 26A and 26C with
the bone interface plate removed.
[0057] FIGS. 27-35 show an alternative method of aligning a knee
surgery according to embodiments of the invention.
[0058] FIG. 36 is a flow chart schematically illustrating a method
for aligning and balancing a knee during knee surgery according to
embodiments of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0059] Embodiments of the present invention provide systems,
devices, and methods for facilitating the alignment and balancing
of the knee during knee replacement surgery and verifying such
balance and alignment. Once the knee is properly aligned, a cut
parallel to a previously made cut on the tibia can be made on the
distal femur. A prosthetic knee placed on these cuts will maintain
the proper alignment of the knee.
[0060] Referring now to FIG. 1, a distal femoral alignment assembly
or component 100 according to embodiments of the invention is shown
in an exploded view. As shown in FIG. 1, distal femoral alignment
assembly 100 can be used for either the left or right knee, i.e.,
one side of the distal femoral alignment assembly may be the medial
side while the other is the lateral side and vice versa. Distal
femoral alignment assembly 100 comprises a main body 101, an
adjustable medial femoral portion coupled to the main body, and an
adjustable lateral femoral portion coupled to the main body. When
the distal femoral alignment assembly 100 is coupled to a distal
femur, the main body or stationary portion of the distal femoral
alignment assembly is generally stationary with respect to the
adjustable medial and lateral femoral portions. The adjustable
medial and lateral femoral portions are adjusted with respect to
the main body. Adjustable medial and lateral femoral portions
respectively comprise medial and lateral paddles 102, 103. The
medial and lateral paddles each comprise anti-rotation shafts 104,
105 which fit into slots 106 of the main body. Medial and lateral
distraction screws 107, 108 respectively couple the medial and
lateral paddles 102, 103 with the main body 101. Distraction screw
capture pegs 109, 110 fix the axial position of the distraction
screws 107, 108 relative to the main body 101 such that rotation of
the medial and lateral distraction screws only adjusts the
positions of the adjustable medial and lateral femoral portions
with respect to the main body 101. The main body comprises mounts
for attachment of a force sensor 111.
[0061] Referring now to FIG. 2, the main body 101 of the distal
femoral adjustment assembly 100 further defines cutting guide
locating apertures on its medial 113a-c and lateral 112a-c sides.
These apertures are cutting guide locating means, e.g., by
facilitating the placement of placement pins from which provide
points of reference for the placement of a cutting guide. The main
body further defines slots or verification attachment slots or
apertures 114a, 114b for attaching a knee alignment verification
means as described below.
[0062] FIGS. 2 and 4 show the distal femoral adjustment assembly
100 unadjusted. FIGS. 3 and 5 show the distal femoral adjustment
assembly 100 adjusted, i.e., the position of one paddle of the
distal femoral adjustment assembly has been moved relative to the
other.
[0063] FIGS. 6 and 7 show a perspective view of a knee alignment
system 99a according to embodiments of the invention. The system
comprises the distal femoral adjustment assembly 100 as described
above. The system further comprises a electronic force-sensing
means or force sensor 115 coupleable with the distal femoral
adjustment assembly 100. As shown, the force sensor 115 comprises a
handheld tool but may alternatively be a smaller device coupleable
with the main body of the distal femoral adjustment assembly 100.
The force sensor 115 senses the force between the medial portion of
the distal femur and the medial portion of the tibial plateau as
well as the force between the lateral portion of the distal femur
and the lateral portion of the tibial plateau, for example, by
comprising first and second force sensing portions 116a, 116b, the
first force sensing portion 116a being a lateral force sensing
portion while the second 116b is a medial force sensing portion and
vice versa. The distal femur and tibial plateau are not shown in
FIGS. 6-7. The force sensor 115 may be similar to those described
U.S. Patent Applications Nos. 61/090,535 entitled "Sensing Force
During Partial and Total Knee Replacement Surgery" (Attorney Docket
No. 021976-000800US) and 61/107,973 entitled "Dynamic Knee
Balancing for Revision Procedures" (Attorney Docket No.
021976-000700US), the entireties of which had been previously
incorporated herein by reference.
[0064] FIG. 8 shows a visual display 117 coupleable with the force
sensor 115. The visual display displays data representative of the
force sensed by the force sensor and may be similar to those
described in U.S. patent application Ser. Nos. 10/973,936, now U.S.
Pat. No. 7,578,821, entitled "Dynamic Knee Balancer with Pressure
Sensing" (Attorney Docket No. 021976-000210US); 61/090,535 entitled
"Sensing Force During Partial and Total Knee Replacement Surgery"
(Attorney Docket No. 021976-000800US); and 61/107,973 entitled
"Dynamic Knee Balancing for Revision Procedures" (Attorney Docket
No. 021976-000700US), the entireties of which had been previously
incorporated herein by reference.
[0065] FIGS. 9-23 show a method of using an exemplary knee
alignment system during knee replacement surgery according to
embodiments of the invention. As shown in FIGS. 9 and 11, the force
sensor 115 is coupled to the distal femoral alignment assembly 100.
As shown in FIGS. 10 and 12, the distal femoral alignment assembly
100 and the coupled force sensor 115 are placed in the gap 120
between the distal femur 118 and the tibial plateau 121 of the
knee. As shown in FIG. 13, the force sensor 115 senses the forces
between the lateral and medial portions of the distal femur and the
tibial plateau. The visual display 117 shows the sensed forces (as
an example, the display shows the forces unbalanced). An adjustment
wrench 122 is coupled to a rotatable distraction screw 107 of the
distal femoral alignment assembly 100. As shown in FIG. 14, when
the unadjusted distal femoral alignment assembly 100 and the
coupled force sensor 115 are first placed in the gap 120 between
the distal femur 118 and the tibial plateau 121, the knee may be
misaligned, i.e., the femoral axis and the tibial axis are not
aligned with each other as in a normal knee. As shown in FIG. 14,
the bottom surface of the distal femoral alignment assembly is
80.degree. relative to the mechanical axis 123 of the femur 118. As
shown in FIG. 15, at least one of the rotatable screws 107, 108 is
rotated with the adjustment wrench 122 to adjust the relative
position of the adjustable medial and/or femoral portions and to
correct the alignment of the knee. Generally, by balancing the
sensed forces in the medial and lateral portions of the knee,
correct alignment of the knee can be achieved (as shown in the
visual display). For example, as shown in FIG. 16, the distal
femoral alignment assembly 100 has been adjusted so that the bottom
surface of the distal femoral alignment assembly is 85.degree.
relative to the mechanical axis 123 of the femur 118.
[0066] The system will typically further comprise a knee alignment
verification means to verify the alignment of the knee by verifying
the angle formed by the mechanical axes of the femur and tibia. As
shown in FIGS. 17 and 18, the knee alignment verification means may
be a laser knee alignment verification member 124 coupleable to the
main body of the distal femoral alignment member 100. As shown in
FIG. 18, the laser knee alignment verification member 124 emits a
femoral laser beam 125a to be aligned along the mechanical axis
123a of the femur and a tibial laser beam 125b to be aligned along
the mechanical axis 123b of the tibia. The angle of the femoral
laser beam and the tibial laser beam relative to each other can be
used by the surgeon to verify the proper anatomical alignment of
the knee, i.e., the angle between the mechanical axes 123a, 123b of
the femur and tibia. Alternatively, as shown in FIGS. 19 and 20,
the knee alignment verification means may be a mechanical knee
alignment verification assembly 126. The mechanical knee alignment
verification assembly 126 comprises a mechanical knee alignment
verification hub 127, a femoral alignment rod 128 coupleable with
the hub 127, and a tibial alignment rod 129 coupleable with the hub
127. The coupled femoral alignment rod 127 can be aligned along the
mechanical axis 123a of the femur 118. The coupled tibial alignment
rod 129 can be aligned along the mechanical axis 123b of the tibia
119. The angle of the femoral alignment rod 128 and the tibial
alignment rod 129 relative to each other can be used by the surgeon
to verify proper alignment of the knee.
[0067] As shown in FIG. 21, the system may further comprise a
plurality of locating pins 130a, 130b. When the knee is properly
aligned, at least one locating pin (130a and/or 130b) may be placed
on the medial side of the distal femur 118 and at least one
locating pin may be placed on the lateral side of the distal femur
as guided by the apertures of the distal femoral alignment
assembly. As shown in FIG. 22, once the locating pins 130a, 130b
are placed on the distal femur 118, the distal femoral alignment
assembly 100 may be disengaged from the distal femur.
[0068] As shown in FIG. 23, the system may further comprise a
distal femoral cutting guide 131 which can be coupled to the distal
femur 118 and positioned based on the position of the locating pins
130a, 130b. Cuts are made on the distal femur 118, for example,
with a surgical saw blades 132. Typically, these cuts will form the
basis for positioning of the femoral portion of an artificial knee.
Exemplary surgical saw blades which may be used to make these cuts
on the distal femur are described co-assigned U.S. Pat. Nos.
6,022,353; 6,503,253; and 6,723,101, the entire contents of which
are incorporated herein by reference.
[0069] Referring now to FIGS. 24A-B, an alternative distal femoral
alignment system 99b is shown including cutting guide 131 for
making a provisional cut on the distal femur in order to mount the
distal femoral alignment assembly 100 flush against the
provisionally cut distal femur. As shown in FIG. 25, angular
graduation marks 133 are provided. The graduation marks correspond
to movement created by adjusting either the medial or lateral
distraction paddles 102, 103 as shown in FIG. 26B. For clarity
purposes, a right distal femur is shown in FIGS. 27-28 and 34-35
and a right knee joint with femur and tibia is shown in FIGS.
29-33. The medial side of components or assemblies of the distal
femoral alignment system shown in FIG. 24 are hereby described
either medial or lateral based on their position when used on a
right knee. Of course, the invention can be used on the left and/or
right knees. Convex shaped pivot fulcrums 500a, 500b are provided
on the surfaces of the distraction paddles 102, 103 which directly
contact the provisionally cut distal femur when the distal femoral
alignment assembly 100 is mounted against the distal femur 118. The
curved surface of the distraction paddles 102, 103 creates fixed
distance fulcrum points to determine how much angle is being
adjusted. FIGS. 26A and 26C show another embodiment of the distal
femoral alignment assembly 100 of the alternative distal femoral
alignment system 99b shown in FIG. 24, which includes bone
interface plate 137. This plate 137 provides protection from convex
shaped distraction paddles 102 and 103 from indenting the softer
cancellous bone exposed as a result of a provisional cut being made
on the distal femur 118 (not shown in FIG. 26). FIG. 26C shows the
bone interface plate 137 sitting on top of convex shaped
distraction paddles 102 and 103 in their unadjusted position.
Shoulder screw 138 is shown, which slips through a loosely fitted
hole 139 in bone interface plate 137 to allow for tilting of bone
interface plate 137 when convex shaped distraction paddles 102 and
103 are adjusted from their unadjusted position to an adjusted
position. Spacing between convex shaped adjustment paddles 102 and
103 is maintained in the medial-lateral direction to provide for a
known pivot fulcrum between the two convex shaped adjustment
paddles, which corresponds to angular graduations 133 shown in FIG.
25. The angular gradations provide an indication of the angle
between the femur and tibia
[0070] Referring now to FIGS. 27-35, a method of using an exemplary
knee alignment system used during knee replacement surgery is shown
according to embodiments of the invention. For purposes of clarity,
a bone cut has already been made on the proximal tibia 119 prior to
the methods described in FIGS. 27-35. FIG. 27 shows provisional
distal femoral cutting guide 131 moveably attached to the
provisionally cut distal femur 118 via two pins 130a and 130b. FIG.
28 shows provisional femoral cutting guide 131 and pins 130a and
130b now having been removed and femoral anterior-posterior cutting
guide 134 is now removably attached to distal femur 118. Saw blade
132 is shown and the anterior and posterior bone cuts are performed
on distal femur 118. FIG. 29 shows now the "extension gap" with the
proximal tibial cut having been made and a provisional distal
femoral cut having been made. The posterior femoral cut has also
been made but hidden from view in FIG. 29. The anterior cut has
also been made on distal femur 118.
[0071] Moving now to FIG. 30, the distal femoral alignment assembly
100 and other components of the distal femoral alignment system 99b
are shown between the proximal tibia 119 and the distal femur 118,
with the leg in full extension. Thickness adapter 133 is shown
moveably coupled to force sensor 115, and force sensor 115 is
moveable coupled to distal femoral assembly 100. Adjustable
posterior member 135a is shown adjacent to a longitudinal slot 400
open on the posterior side of distal femoral assembly 100, with the
slot closed on the anterior side of the distal femoral assembly
100. FIG. 31 shows adjustable posterior member 135a having now been
moveably coupled within the longitudinal slot 400 along the medial
side of distal femoral assembly 100. Moveable coupling means 136a,
136b can include magnets or other common coupling means such as
screws or spring clips. Longitudinal slots are also provided on the
opposite side of the distal femoral assembly 100. Longitudinal
slots along the sides of distal femoral assembly 100 are of
adequate length to allow for anterior-posterior adjustment of
adjustable posterior member to abut the previously made posterior
cut 401 of the distal femur 118. The adjustable posterior members
further balance extension filling the posterior space with a
condylar thickness similar to the posterior condylar thickness of
the femoral component to be implanted thus taking into account
soft-tissue tendencies, or bias. FIG. 32 shows components and
assemblies of the distal femoral alignment system 99b now
completely in place between the proximal tibia and the distal femur
and force readings coupled from force sensor 115 are being
displayed on display 117, It is understood that display 117 may be
integral to force sensor 115. The display 117 can also be separable
from the sensor. The display 117 is showing force readings of 5 and
2 lateral and medial respectively, indicating lower force between
the medial side of the distal femur and the medial side of the
proximal tibia, in this example. Adjustment wrench 122 is shown in
line with the medial distraction screw 107. FIG. 33 shows the
medial distraction paddle 102 having now been adjusted to a point
wherein the forces being measured by sensor 115 and displayed by
display 117 read 5 on both the lateral and the medial side. Pin
130a is shown being driven through a lateral side cutting guide
locating aperture and pin 130b has yet to be driven through the
medial side cutting guide locating aperture. FIG. 34A shows both
pins having now been driven through cutting guide locating
apertures of distal femoral assembly 100, and distal femoral
assembly 100 now having been removed from the distal femur 118.
Cutting guide 131b is positioned over pins 130a and 130b. FIG. 34B
shows cutting guide 131b now positioned over pins 130a and 130b and
saw blade 132 will be used to make the final distal femoral cut at
an angle "A" which is the plane of balanced resection as determined
by the force sensor. FIG. 35 shows femoral anterior-posterior
cutting guide 134 now removably coupled to distal femur 118 and saw
blade 132 is shown making a final cut on the anterior distal femur.
Anterior and posterior chamfer cuts will also be made on the distal
femur 118 at this point.
[0072] While the above is a complete description of the preferred
embodiments of the invention, various alternatives, modifications,
and equivalents may be used. Therefore, the above description
should not be taken as limiting in scope of the invention which is
defined by the appended claims.
* * * * *