U.S. patent application number 14/052569 was filed with the patent office on 2014-02-06 for method and apparatus for computer aided surgery.
The applicant listed for this patent is Osvaldo Andres Barrera, Hani Haider. Invention is credited to Osvaldo Andres Barrera, Hani Haider.
Application Number | 20140039520 14/052569 |
Document ID | / |
Family ID | 38919895 |
Filed Date | 2014-02-06 |
United States Patent
Application |
20140039520 |
Kind Code |
A1 |
Haider; Hani ; et
al. |
February 6, 2014 |
METHOD AND APPARATUS FOR COMPUTER AIDED SURGERY
Abstract
A number of improvements are provided relating to computer aided
surgery. The improvement relates to both the methods used during
computer aided surgery and the devices used during such procedures.
Some of the improvement relate to controlling the selection of
which data to display during a procedure and/or how the data is
displayed to aid the surgeon. Other improvements relate to the
structure of the tools used during a procedure and how the tools
can be controlled automatically to improve the efficiency of the
procedure. Still other improvements relate to methods of providing
feedback during a procedure to improve either the efficiency or
quality, or both, for a procedure.
Inventors: |
Haider; Hani; (Carter Lake,
IA) ; Barrera; Osvaldo Andres; (Omaha, NE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Haider; Hani
Barrera; Osvaldo Andres |
Carter Lake
Omaha |
IA
NE |
US
US |
|
|
Family ID: |
38919895 |
Appl. No.: |
14/052569 |
Filed: |
October 11, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11764505 |
Jun 18, 2007 |
8560047 |
|
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14052569 |
|
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60814370 |
Jun 16, 2006 |
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60827877 |
Oct 2, 2006 |
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Current U.S.
Class: |
606/130 |
Current CPC
Class: |
A61B 17/1675 20130101;
A61B 2034/105 20160201; A61B 34/25 20160201; A61B 2034/102
20160201; A61B 17/1703 20130101; A61B 2034/2055 20160201; A61B
2017/00199 20130101; A61B 2090/3937 20160201; A61B 2017/00725
20130101; A61B 34/10 20160201; A61B 2034/107 20160201; A61B
2017/00221 20130101; A61B 2017/320052 20130101; A61B 34/30
20160201; A61B 17/142 20161101; A61B 2090/065 20160201; A61B 90/36
20160201; A61B 2090/0812 20160201; A61B 2034/101 20160201; A61B
2090/365 20160201; A61F 2002/4632 20130101; A61B 2034/2068
20160201; A61B 17/15 20130101; A61B 2090/372 20160201; A61B
2017/00026 20130101; A61B 2034/256 20160201; A61B 90/11 20160201;
A61B 2090/395 20160201; A61B 2017/00212 20130101; A61B 2090/367
20160201; A61B 17/1764 20130101; A61B 2034/104 20160201; A61F
2002/4633 20130101; A61B 34/20 20160201; A61B 17/1626 20130101;
A61B 90/90 20160201; A61B 2090/061 20160201; A61B 2034/258
20160201; A61B 17/154 20130101; A61B 2034/2072 20160201; A61B
2034/108 20160201; A61B 2034/254 20160201 |
Class at
Publication: |
606/130 |
International
Class: |
A61B 19/00 20060101
A61B019/00 |
Claims
1. A hand held surgical tool comprising: a housing having a distal
end and a proximal end; a shaft having a distal end adapted to
engage tissue at a pre-determined surgical site, the shaft disposed
within and moveable relative to an interior portion of the housing;
an actuator coupled to the shaft and configured to provide
controllable movement of the shaft relative to the distal end of
the housing; one or more elements coupled to an exterior portion of
the housing for use in detecting a position and orientation of the
surgical tool; and a processor attached to or coupled to the
housing, the processor in communication with the actuator and
having instructions to control the operation of the actuator for
controllable movement of the shaft in response to a signal received
from a surgical computer.
2. The tool of claim 1, wherein the signals received by the
processor to operate the actuator are based on a surgical plan for
a patient anatomy within the pre-determined surgical site and a
position and orientation of the surgical tool relative to the
patient anatomy within the pre-determined surgical site, the
position and orientation obtained using the one or more
elements.
3. The tool of claim 2, wherein the surgical computer is configured
to correlate the position and orientation of the surgical tool to
the surgical plan for the patient anatomy within the pre-determined
surgical site.
4. The tool of claim 2, wherein when the distal end of the shaft is
engaged with tissue a portion of the patient anatomy in the
pre-selected surgical site is marked.
5. The tool of claim 4, wherein the patient anatomy is a bone.
6. The tool of claim 5, wherein the mark comprises a visible
mark.
7. The tool of claim 1, wherein the one or more elements for
detecting the position and orientation of the surgical tool are
part of a reference frame.
8. The tool of claim 1, wherein the one or more elements for
detecting the position and orientation of the surgical tool include
a plurality of position markers.
9. A surgical system comprising the tool of claim 1, further
comprising an optical tracking system configured to optically track
the one or more elements to detect the position and orientation of
the surgical tool.
10. The surgical system of claim 9, wherein the optical tracking
system is configured to communicate the position and orientation of
the surgical tool to the surgical computer.
11. A surgical system comprising the tool of claim 2, further
comprising a monitor configured to display the movement of the hand
held surgical tool in real time.
12. The surgical system of claim 11, wherein the monitor is further
configured to display a portion of the surgical plan for the
patient anatomy within the pre-determined surgical site.
13. The surgical system of claim 12, wherein the patient anatomy is
a portion of a femur or a tibia or a knee.
14. The tool of claim 1, wherein the processor communicates with
the surgical computer through a wired connection.
15. The tool of claim 1, wherein the processor communicates with
the surgical computer through a wireless connection.
16. The tool of claim 1, wherein the actuator is an
electromechanical actuator.
17. The tool of claim 1, wherein the range of the actuator movement
is configured to extend the distal end of the shaft past the distal
end of the housing.
18. The tool of claim 2, wherein the surgical plan includes a plan
for a total knee replacement surgery.
19. The surgical tool of claim 1, wherein the hand held surgical
tool includes a surface for manually grasping the device.
20. A surgical system comprising: a surgical computer; a hand held
surgical tool comprising: a housing having a distal end and a
proximal end; a shaft having a distal end adapted to engage tissue
at a pre-determined surgical site, the shaft disposed within and
moveable relative to an interior portion of the housing; an
actuator coupled to the shaft and configured to provide
controllable movement of the shaft relative to the distal end of
the housing; one or more elements coupled to an exterior portion of
the housing for use in detecting a position and orientation of the
surgical tool; and a processor attached to or coupled to the
housing, the processor in communication with the actuator and
having instructions to control the operation of the actuator for
controllable movement of the shaft in response to a signal received
from a surgical computer; and a monitor for displaying the position
of the hand held surgical tool.
21. The surgical system of claim 20, further comprising an optical
tracking system configured to optically track the one or more
elements for detecting the position and orientation of the surgical
tool.
22. A method for marking a patient, the method comprising: creating
a three dimensional representation of a portion of the patient to
which a bone or tissue cutting procedure is to be performed;
identifying an area of the three dimensional representation
corresponding to a portion of bone or tissue for which the
procedure is to be performed; tracking a guided surgical tool to
determine a position and orientation of the tool relative to the
portion of bone or tissue; marking a portion of the bone or tissue
with a tissue engaging portion at a distal most end of a shaft
extending from the guided surgical tool; and operating an actuator
coupled to a housing of the guided surgical tool in response to an
indication that the tissue engaging portion of the distal most end
of the shaft is in an undesired position, the operating step
providing relative movement between the shaft and the housing to
prevent engagement of the distal most end of the shaft with the
bone or tissue.
23. The method of claim 22, wherein the surgical tool is a freehand
surgical tool.
24. The method of claim 22, wherein marking includes modifying a
surface of the portion of the bone or tissue.
25. The method of claim 22, further comprising comparing the three
dimensional representation of the portion of the patient to the
position and orientation of the tool using a surgical computer.
26. The method of claim 22, wherein tracking the surgical tool
includes using an optical tracking system to track a reference
frame on the surgical tool.
27. The method of claim 22, further comprising guiding the surgical
tool to mark the portion of bone or tissue with an outline
corresponding to a shape of a preselected prosthesis.
28. The method of claim 27, wherein the prosthesis is a femoral
implant.
29. The method of claim 21, further comprising guiding the surgical
tool to mark the portion of bone or tissue with lines corresponding
to cut planes for a total knee replacement procedure.
30. The method of claim 29, further comprising preselecting the
lines corresponding to cut planes based on the three dimensional
representation of the portion of the patient and a configuration of
a preselected prosthesis.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/764,505, filed Jun. 18, 2007, titled
"Method and Apparatus for Computer Aided Surgery," which
application claims priority from U.S. Provisional Application No.
60/814,370, filed Jun. 16, 2006, titled "Method and Apparatus for
Computer Aided Orthopaedic Surgery," and U.S. Provisional
Application No. 60/827,877 dated Oct. 2, 2006, titled "Method and
Apparatus for Computer Aided Surgery," the disclosures of each of
which are herein incorporated by reference in their entirety.
INCORPORATION BY REFERENCE
[0002] All publications and patent applications mentioned in this
specification are herein incorporated by reference to the same
extent as if each individual publication or patent application was
specifically and individually indicated to be incorporated by
reference.
FIELD
[0003] The present invention relates to the field of computer
assisted surgery. Specifically, the present invention relates to
various aspects of a surgical suite in which a computer provides
guidance or assistance during a surgical procedure.
BACKGROUND
[0004] Many surgical procedures are complex procedures requiring
numerous alignment jigs and intricate soft tissue procedures.
Preparing and placing the alignment jigs and other preparation is
often a significant part of the procedure. For instance, when
performing a total knee replacement procedure ("TKR"), the
prosthesis must be accurately implanted to ensure that the joint
surfaces are properly aligned. If the alignment is inaccurate, the
misalignment will lead to failure of the joint, requiring the
complex task of replacing one or more portions of the knee
prothesis.
[0005] To ensure that the prosthesis is accurately implanted,
during a TKR procedure, the surgeon uses a variety of jigs to guide
the cutting of the femur and the tibia. The jigs are complex
devices that require significant time to install on the patient
during the surgical procedure.
[0006] The advent of computer assisted surgery provides the promise
of simplifying many of the complexities of surgical procedures. In
some instances, the computer may be used to guide the surgeon
during the process. Although computer assisted surgery holds
promise, there are numerous aspects to be addressed to make a
system commercially viable. For instance, in addition to improving
the efficiency of the procedures, the quality of the resulting
procedures should be addressed. Accordingly, there continues to
exist numerous aspects of computer assisted surgery that require
improvement to improve the efficiency and/or quality of the
procedure. The end result will encourage medical professionals to
migrate toward computer assisted surgical systems.
SUMMARY OF THE DISCLOSURE
[0007] In light of the foregoing, a computer assisted surgical
suite having a number of improvements is provided. For instance, a
surgical suite having a computer and a surgical tool that
communicates with the computer may be provided. The system also
includes a tracking element for tracking the position of the
surgical tool. In one aspect, the system allows the surgeon to
perform a surgical procedure on a virtual model of the patient
using the surgical tool. As the surgeon performs the procedure on
the virtual model, the computer stores the information regarding
the sequence of the steps performed and the position of the
surgical tool during the procedure. Once the surgeon is satisfied
with the results on the virtual model, the stored information can
be used during the procedure to assist or guide the surgeon.
[0008] According to a further aspect, the computer controls
operation of the surgical tool in response to information detected
regarding the surgical tool. For instance, the system may track the
position of the surgical tool relative to the patient. Based on the
data regarding the position of the surgical tool, the computer may
send signals to the surgical tool to control the operation of the
surgical tool, such as reducing the speed on the tool or turning
the tool on or off.
[0009] According to another aspect, the system provides a
communication link between the surgical tool and the computer
system that allows the surgical tool to control operation of the
computer system and the computer system to control operation of the
surgical tool.
[0010] Another aspect of the system is directed toward the use of
the surgical tool in a free hand procedure to reduce or eliminate
the use of jigs during a procedure. In such a procedure, the
computer tracks the position of the surgical tool relative to the
patient and displays the results on a screen to guide the surgeon
in the procedure. In a resection procedure, the system may be
configured to identify the patient tissue with different colors to
identify the proximity of the tissue to the resection boundaries.
For instance, tissue that is not to be resected may be illustrated
in a red color, so that the surgeon can easily see that the tissue
is not to be resected. Tissue that is to be resected may be
illustrated in a green color. Further, tissue at the boundary of
the portion to be resected may be illustrated in yellow, so that
the surgeon can easily see that the cuts are getting close to the
boundary.
[0011] Yet another aspect of the system is directed toward
improving the display of information during a surgical procedure.
Specifically, depending on which portion of a procedure is being
performed, the surgeon may desire to change the view of the
information being displayed. It can be cumbersome to change the
view in the middle of a procedure to a different view. Accordingly,
the system can be used to automatically switch to a particular view
based on the position of the surgical tool. Additionally, the
surgeon may program this information before a procedure, or the
system can learn to recognize that a particular surgeon desires a
particular view based on inputs from the surgeon during various
procedures.
[0012] According to a further aspect, the system provides a method
for assessing and improving the quality of a bone cut. For
instance, the system measures various parameters relating to the
quality of a bone cut, such as surface roughness, accuracy of each
cut. If the parameter fall within pre-defined limits, the system
indicates to the surgeon that the resection was successful, so that
the prosthesis can be implanted. If one or more parameter falls
outside the pre-defined limits, the system may calculate the step
or steps necessary to correct the bone cuts so that the surgeon can
perform the necessary correction.
[0013] Another aspect of the invention is directed improving the
monitoring of the surgical tool. For instance, in certain aspects
of computer assisted surgery, the position of certain surgical
tools may be quite important in assessing the steps necessary
during the procedure. However, during the procedure, operation of
the surgical tool may cause the tool to deflect. The deflection may
result in the system misidentifying the actual position of the
surgical tool. Accordingly, the present system may include one or
more sensors for detecting deflection of a portion of the surgical
tool and an element for modifying the tracking element in response
to the detected deflection.
[0014] A still further aspect of the present invention is directed
to a marker that is used for marking tissue to be resected. The
marker includes an actuator that responds to signals from the
computer system. A tracking element provides data to the computer
regarding the position of the marker. Based on the position of the
marker, the computer controls the marker between an extended
position and a retracted position. Specifically, if the computer
detects that the marker is on a portion of the patient that is to
be marked, then the computer controls the marker to extend the
marker to the extended position so that a tip of the marker is
exposed to mark the patient. Alternatively, if the marker is on a
portion of the patient that is not to be marked, the computer
controls the marker to retract the tip of the marker so that the
marker cannot mark the patient.
[0015] The foregoing and other aspects of the present invention are
described in greater detail in the detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a diagrammatic view of a computer assisted
surgical suite.
[0017] FIG. 2 is a diagrammatic view of a surgical tool of the
surgical suite of FIG. 1.
[0018] FIG. 3 is an alternative diagrammatic view of a computer
assisted surgical suite.
[0019] FIG. 4 is a fragmentary view of a surgical tool of the
surgical suite of FIG. 1.
[0020] FIG. 5 is an alternative embodiment of the surgical tool
illustrated in FIG. 4.
[0021] FIG. 6 is plot illustrating data regarding the surface
roughness and surface waviness.
[0022] FIG. 7 illustrates a separation of the surface waviness and
surface roughness of a surface profile.
[0023] FIG. 8 is a table illustrating the various potential error
in fitting an implant.
[0024] FIG. 9 is a measuring block for assessing the fit of an
implant.
[0025] FIG. 10 illustrates the femur cuts for a total knee
replacement procedure.
[0026] FIG. 11 is a diagram illustrating the error angle for bone
cuts in a total knee replacement procedure.
[0027] FIG. 12 is a diagram illustrating the steps of a method for
programming a surgical robot.
[0028] FIG. 13 is a diagrammatic illustration of a navigable
marking pen.
[0029] FIG. 14 is a registration block for registering tools of a
surgical instrument.
[0030] FIG. 15 is a registration pointer operable in connection
with the surgical suite illustrated in FIG. 1 or FIG. 3.
[0031] FIG. 16 is an alternative embodiment of a surgical tool
operable in connection with the surgical suite of FIG. 1 or FIG.
3.
[0032] FIG. 17 is a block diagram of the wireless features of the
surgical suite illustrated in FIG. 3.
[0033] FIG. 18 is a top view of an alternative cutting blade
operable in connection with a surgical saw.
[0034] FIG. 19 is a bottom view of the cutting blade illustrated in
FIG. 18.
DETAILED DESCRIPTION
[0035] Referring now to the figures, wherein like elements are
numbered alike throughout, a surgical suite for computer assisted
surgery is designated generally 50. The suite 50 includes a first
computer 70 for pre-operative use. For example, pre-operative
analysis of the patient and selection of various elements may be
performed on the first computer. The suite may also include a
second computer 80, referred to as the OR computer, which is used
during a procedure to assist the surgeon and/or control one or more
surgical instruments. In addition the suite may include a computer
(standalone or collaborating with 80) mounted on the surgical
instrument. First computer 70 is provided in the present instance,
but may be omitted in some configurations because the functions of
computer 70 are also implemented on OR computer 80, which can be a
standalone. Moreover the whole `pre-surgical planning` may
eventually happen instantaneously inside the OR. Nevertheless, if
desired for particular applications, first computer 70 may be used.
Furthermore, the micro-processing system of the system 50 can
reside in the cutting instrument. In such a configuration, the
computations and user interface can be performed within a computer
on the surgical tool. Such system performs error analysis of
location of the cutting instrument relative to the ideal cut to be
performed, and displays corrective actions and other information on
a screen mounted to the instrument.
[0036] The suite 50 may include a tracking/navigation system that
allows tracking in real time of the position in space of several
elements, including: (a) the patient's structures, such as the bone
or other tissue; (b) the navigable surgical tools, such as the bone
saw 100, which is controlled by the surgeon based on information
from the OR computer 80 or (c) surgeon/assistants system specific
tools, such as a pointer, registration tools, or other objects. The
OR computer 80 may also perform some control on the cutting
instrument trough the implemented of the present configuration of
the system. Based on the location of the tool, the system 80 is
able to vary the speed of the surgical tool 100 as well as turn the
tool off to prevent potential damage. Additionally, the suite 50
may also include a surgical robot 200 that is controlled by the OR
computer 80. The features of the navigable tool 100 and the
surgical robot 200 may vary. The details of several desirable
features are described in greater detail below. The various
features can be selected as desired for a particular practice or
situation. In the following description, the only surgical
instrument shown in figures is the navigated saw 100. Nonetheless,
many others instruments can be controlled and/or navigated as
explained above, such as a drill, burr, scalpel, stylus, or other
instrument. Therefore in the following discussion, the system is
not limited to the particular tool described, but has application
to a wide variety of instruments.
[0037] As discussed further below, one exemplary use of the
surgical suite incorporates the use of a virtual model of the
portion of the patient upon which a procedure is to be performed.
Specifically, prior to a procedure, a three dimensional model of
the relevant portion of the patient is produced using CT scans, MRI
scans or other techniques. Prior to surgery, the surgeon may view
and manipulate the patient model to evaluate the strategy for
proceeding with the actual procedure.
[0038] One potential methodology uses the patient model as a
navigation device during a procedure. For instance, prior to a
procedure, the surgeon may analyze the virtual model of a portion
of the patient and map out the tissue to be resected during a
procedure. The model is then used to guide the surgeon during the
actual procedure. Specifically, during the procedure a tracking
mechanism monitors the progress of the procedure and the results
are displayed in real time on the OR computer 80 so that the
surgeon can see the progress relative to the patient model.
[0039] To provide navigation assistance during a procedure, the
system 50 includes a position detection device 120 that monitors
the position of the surgical tool 100. The surgical tool 100
includes one or more position markers 105 that identify pre-defined
points of reference on the tool. In the present instance the
surgical tool includes several markers 105 which, together with
some pre-defined points of reference on the tool, identify the tool
and its location.
[0040] Although a variety of position tracking systems can be used,
one exemplary system is the NDI Polaris optical measurement system
produced by Northern Digital Inc. The system uses a position sensor
and both active and passive markers. The active markers may be
wired sensors that are electrically connected to the system. The
active markers emit infrared light that is received by the position
sensor. The passive markers are wireless markers that need not be
electrically connected to the system. The passive markers reflect
infrared light back to the position sensor. Typically, when using
passive markers, the position sensor floods the field of view with
infrared light that is then reflected back to the position sensor
from the passive markers. The position sensor includes an infrared
receiver and it receives light emitted light from the active
markers and reflected light from the passive markers. The position
system triangulates the three dimensional position of the tool
based on the position of the markers. In the present instance, the
position detection device 120 is also operable to detect the
orientation of the tool relative three orthogonal axes. In this
way, the position detection device 120 determines the location and
orientation of the tool 100.
[0041] The position detection device 120 is linked with the OR
computer 80 so that the data regarding the position of the surgical
tool 100, the patient's anatomy, and other system specific tools,
is communicated to the OR computer. The computer uses this
information to track the progress of a procedure.
[0042] To track the position of the surgical tool 100 relative to
the patient, position marker is attached to the portion of the
patient on which the procedure is to be performed. The position
marker attached to the patient may be similar to the position
marker 105 attached to the surgical tool 100, as shown in FIG. 4.
The position marker on the patient is correlated to a corresponding
point on the virtual model of the patient. In this way, the
registration point positions the tool relative to the patient and
the patient relative to the virtual model.
[0043] A series of points are used to register or correlate the
position of the patient's anatomy with the virtual model of the
patient. To gather this information, a navigated pointer is used to
acquire points at an anatomical landmark or a set of points on a
surface within the patient's anatomy. A process referred to
morphing may be used to register the patient to the virtual model
of the patient. During such a process, the surgeon digitizes parts
of the patient and some strategic anatomical landmarks. The
computer 80 analyzes the data and identifies common anatomical
features to thereby identify the location of points on the patient
that correspond to particular points on the virtual model.
[0044] Accordingly, as set forth above, the position detector
monitors the position of several items in real time, including: the
position of the surgical tool 100, the position of the patient and
the position of items used during a procedure, such as a pen or
marker as described further below. Accordingly, the computer
combines the data regarding the position of the surgical tool 100,
the data regarding the position of the patient, and the data
regarding the model of the patient. This combination is used to
provide a real time model of the position of the tool relative to
the patient, which can be viewed by the surgeon on the monitor.
Further still, as previously described, prior to a procedure, the
surgeon may analyze the patient model and identify the tissue that
is to be resected. This information can then be used during the
procedure to guide the surgeon.
[0045] During the procedure, the monitor displays a model of the
surgical tool relative to the patient model, which reflects the
real time position of the tools, such as the surgical tool 100,
relative to the patient. The surgeon can align the position of the
tool 100 by viewing the position of the image of the tool relative
to the patient model on screen. Once the monitor shows the virtual
tool to be aligned with the portion of the patient model identified
for resection, the surgical tool is properly aligned on the
patient. In this way, the doctor can align the tool without the
need for complex jigs or fixtures. Further, as the tool 100
intersects the patient, the data regarding the position of the tool
and the patient model is correlated to show the result of the tool
intersecting the patient. In this way, the computer can analyze and
display the progress of a procedure in real time. As the tool 100
cuts patient tissue, the monitor displays the tissue being removed
from the patient model. Therefore, in addition to guiding the
position of the tool, the OR computer can be used to guide the
surgeon as to what tissue should be resected during a
procedure.
[0046] In addition to including a surgical tool controlled by the
surgeon, the suite 50 may include a surgical robot 200. The
surgical robot can be programmed to perform one or more operations
during a medical procedure. The surgical robot 200 is controlled by
the OR computer, which is programmed with the instruction set for
the procedure. As with the navigation system described above, when
using the robot, the position detection device 120 monitors the
position of the surgical robot, and prior to the procedure the
location of the patient is identified so that the computer has data
regarding the position of the surgical robot relative to the
position of the patient.
Assessing and Correcting Bone Cuts
[0047] When implanting a prosthetic onto a bone, the surgeon must
resect portions of the bone to prepare the bone to receive the
prosthetic. Regardless of how the resection is performed, it is
important to assess the quality of the cuts performed during a
procedure prior implanting the prosthetic. Bad fit between the bone
and the prosthetic causes a significant number of implant failures.
Therefore, a close match between the shape and dimensions of the
prepared bone and the prosthetic is important to the proper
affixation and durability of the implant. The surgeon may rely upon
experience and trial and error during a procedure, however, doing
so does not provide a quantifiable method for ensuring that a
resection is proper.
[0048] Accordingly, it may be desirable to incorporate a method and
apparatus for assessing the quality of bone cuts before a
prosthetic is implanted. Additionally, after assessing the bone
cuts, it may be desirable to provide feedback regarding any
additional shaping that should be made to improve the bone cuts to
prepare the bone to receive the implant.
[0049] The steps for assessing and correcting bone cuts will not be
described. First, the bone is resected according to the geometry of
the prosthetic to be implanted. The resected bone is then scanned
in three dimensions or digitized to obtain a three dimensional
image of the bone. The scanned geometrical image is then analyzed
to evaluate various criteria of the bone cuts. Based on the
analysis of the scanned image, suggestions may be provided to the
surgeon directly in the operating room before the prosthesis is
implanted. In this way, the system provides feedback to the surgeon
to allow for additional modifications to be made to the resected
bone to improve the fit with the prosthesis.
[0050] Referring to FIG. 1, the system for assessing the bone cut
comprises a scanning device 320 that communicates with a processor,
such as a personal computer, which may be the OR computer 80. The
processor communicates with an output device, such as a monitor 85
to illustrate information about the assessment of the bone
cuts.
[0051] The scanning device 320 may be one of a number of various
devices for acquiring information regarding the three dimensional
configuration of an object. The scanner may use electromagnetic,
ultrasonic/acoustic, mechanical, infra-red line-of site, or other
elements. For instance, a three dimensional optical laser scanner,
scriber, navigated digitizer, coordinate measuring machine or
CT-based digitization can be used to create a digital model of the
bone surface.
[0052] The processor analyzes the scanned data to evaluate each cut
of the resected bone. For instance, in the case of a TKR procedure,
there are typically five separate cuts made to the femur when the
bone is resected to accommodate the prosthetic (it may be
considered seven cuts rather than five when considering the
posterior condyle resection as two cuts, as well as the posterior
chamfer). The image data for the resected bone is analyzed to
assess the surface finish for each of the five cuts. During the
evaluation of the image data, the processor may evaluate several
characteristics, including, but not limited to, surface finish, fit
error (i.e. looseness), location error (alignment error), and the
accuracy of each cut. Each of these characteristics is discussed
below in greater detail.
[0053] Surface finish may include one or more characteristics to
evaluate whether the surface is of sufficient quality to bond well
with the prosthetic. In the present instance, the system analyzes
the roughness and/or the waviness of the resected surface to assess
the surface finish. Roughness includes the finer irregularities of
a surface that generally result from a particular cutting tool and
material conditions. Waviness includes the more widely spaced
deviation of a surface from the nominal or ideal shape of the
surface. Waviness is usually produced by instabilities, such as
blade bending, or by deliberate actions during the cutting process.
As illustrated in FIG. 7, waviness has a longer wavelength than
roughness, which is superimposed on the waviness.
[0054] Based on analysis of the 3D geometrical image data, the
surface finish for each cut is analyzed and quantified. In the
present instance, the surface finish may be quantified based on:
(1) the roughness average, (2) an average of the heights of a
select number of the worst peaks (i.e. highest surface peak
relative to ideal surface); (3) an average of the heights of a
select number of the worst valleys (i.e. deepest valley relative to
ideal surface); and (4) a measure of the deviation from the average
height of the worst peaks and the average depth of the worst valley
(i.e. (2)-(3)). In some instances, it may be desirable to separate
the quantification of the measure of waviness from the measure of
roughness. However, in the present instance, roughness and waviness
are evaluated together. An example of a resected femur having
unacceptable surface finish is illustrated in FIG. 8. As can be
seen, the geometry of the resection is proper, so that the
prosthetic would fit properly onto the resected bone and be
properly aligned. However, due to the poor surface finish it is
likely that the bond between the bone and the prosthetic will fail
prematurely.
[0055] In addition to surface finish, it is desirable to analyze
the fit error of resected bone. Fit represents the looseness or
play between the implant and the resected bone shape prior to
affixing the prosthetic to the bone. An example of a resected femur
having an unacceptable fit error is illustrated in FIG. 8. As can
be seen, the surface of each cut is acceptable and the orientation
of each cut is acceptable, however, the resultant shape leaves
unacceptable gaps between the prosthetic and the resected bone. The
gaps create play or looseness that will lead to misalignment and/or
premature failure of the bond between the bone and the
prosthetic.
[0056] To measure the fit error, a fitness measuring block 340 may
be utilized. The fitness measuring block 340 is a block having an
internal shape corresponding to the internal shape of the
prosthetic (i.e. the surface that will bond with the bone). A
sensor 345 for detecting displacement is attached to the fitness
measuring block. In the present instance, the sensor is an infrared
tracking device. Alternatively, a navigated implant trial that is
specific to each prosthetic implant may be used rather than a
measuring block. The navigated implant trial is an implant similar
to the prosthetic that is to be implanted into the patient. The
navigated implant includes an element for detecting the position of
the implant trial, such as the sensor 345 described above. The
tracking device 120 (see FIG. 1) tracks the position of the
tracking sensor 345 and communicates data to the processor that is
indicative of displacement of the fitness measuring block relative
to the resected bone.
[0057] The measuring block 340 is placed over the resected bone.
The surgeon then attempts to move the measuring block in all
directions relative to the bone to evaluate translational error
based on the amount of translation possible between the measuring
block and the resected bone. Specifically, the surgeon rotates the
block in flexion and extension, as well as internally and
externally. In other words, the surgeon rotates the blocks about
several axis relative to the bone, such as an axis running
generally parallel to the axis of the bone (i.e. rotation
internally and externally) as well as an axis running generally
transverse the axis of the bone (i.e. rotation in flexion and
extension). As the surgeon moves the measuring block, the sensor
detects the translational and rotational movement relative to the
bone and communicates the data with the processor (such as OR
computer 80). Based on the data from the sensor 345 and/or position
detection element 120, the processor analyzes and quantifies the
fit based on the measured translational error and the measured
rotational error.
[0058] A third characteristic for assessing the cuts is the
location of the cuts, which is the location that the implant may be
positioned. The third parameter relates to error of the final
position case of a tight fit or minimum possible error in case of
looseness after the bone is cut and before the prosthetic is
cemented. The assessment is performed using the same data set that
was collected while analyzing the implant fit as described
above.
[0059] The location error is quantification of the deviation of the
location of the measuring block from the ideal location at which
the implants are to be positioned. Specifically, in the present
instance, the location error is based on three rotational
deviations and three translational deviations from the ideal
locations. In the case of the trial stage, before drilling the
holes for the stems of the implant, only two translational errors
are considered. The holes are drilled to accommodate one or more
alignment stems that are located on the interior of the implant.
Once the holes are drilled, the holes constrain the position of the
implant relative to the patient. Accordingly, prior to drilling the
holes it may be desirable to assess the cuts. After analyzing
and/or modifying the cuts, the system may be used to guide the
holes to be drilled. As part of the assessment process, the
measuring block is manipulated to account for medial and lateral
deviation because of constraints in other directions. In this way,
depending on the procedure being analyzed, the directions in which
the block is manipulated may vary.
[0060] In the foregoing description, the evaluation of the location
error and fit error are based on measurements provided by
manipulating the fit measurement block 340 relative to the resected
bone. Alternatively, the fit and location errors may be evaluated
using a virtual comparison of the resected bone and models of ideal
location and fit for the bone. For instance, as described above,
the resected bone may be scanned to create a three dimensional
model of the resected bone. Prior to the procedure a three
dimensional model of the relevant portion of the patient can be
created using any of a variety of techniques, including but not
limited to CT scans and MRI images. The processor may include a
database of models corresponding to various prosthetics. The
surgeon selects the appropriate prosthetic model and positions it
relative to the model of the relevant portion of the patient. The
processor then modifies the patient model to reflect the ideal
resected surfaces for the selected prosthetic. Using collision
detection algorithms, the scanned data for the resected bone can be
compared with the data for the model for the ideal resected bone to
calculate the various criteria used to measure fit error and
location error.
[0061] A final characteristic used in the present instance to
evaluate the bone cuts is the accuracy of each cut. For example, in
the instance of a TKR procedure, the accuracy of each cut is
evaluated. The importance of the accuracy of the cuts is
exemplified by the third sample illustrated in FIG. 8. As can be
seen, the sample has acceptable surface finish, fit and location.
In other words, the prosthetic will fit well on the bone (i.e. it
won't wiggle excessively), the surface finish is not too rough or
wavy and the prosthetic will be properly aligned with the bone.
However, due to the inaccuracy in one or more of the cuts, there
will be gaps between the prosthetic and the bone that will increase
the likelihood of premature failure.
[0062] To evaluate the accuracy of the cuts, the deviation between
the actual cuts and the ideal cuts for the particular prosthetic is
measured. The ideal cuts are determined based on the geometry of
the prosthetic to be implanted on the resected bone. For instance,
in the example of a TKR, the ideal cuts for the femur are based on
the internal configuration of the femoral prosthetic. One way of
determining the ideal cuts is to create a model of the
configuration of the ideal cuts for the patient, as described
above
[0063] As described above in connection with evaluating the surface
finish, in the present instance, a scanner 320 (shown in FIG. 1) is
used to create a model of the resected bone. The data obtained from
the scanner 320 for each planar resected surface is compared with
the data for the corresponding surface of the ideal resected model
to evaluate the accuracy of the cuts. The quantification of the
accuracy can be based on a variety of measurements regarding the
deviation of each resected surface from the ideal surface. In the
present instance, four characteristics are measured. The first
characteristic is a translational measurement, and it is calculated
as the distance between the plane of the resected surface to the
centroid of the corresponding ideal cut. The remaining three
characteristics are rotational angles. The first rotational
characteristic is the orientation of the resected surface relative
to the ideal plane with respect to a first axis; the second
rotational characteristic is relative to a second axis and the
third rotational characteristic is relative to a third rotational
axis. These characteristics are measured and correlated to quantify
the accuracy of each planar cut of the resected bone.
[0064] After the processor determines the various criteria to
assess the quality of the cuts, the information regarding the
criteria may be displayed on the monitor to indicate to the surgeon
whether or not the cuts were of sufficient quality to proceed with
implanting the prosthetic on the bone. Additionally, if the cuts
are not of sufficient quality, the processor may evaluate the cuts
to determine a strategy for modifying the resected bone to improve
the quality of the cuts. For instance, based on a comparison of the
scanned data for a resected bone with the data for the model of an
ideal resected bone, the processor may determine the portion(s) of
bone that should be re-shaped to improve the correlation between
the resected bone and the model for the ideal resected bone. After
determining the portions of the bone that should be re-shaped, such
changes are displayed on the monitor to show the surgeon which
portion(s) of the bone should be removed. For example, using a
graphical output, the bone may be illustrated generally in white
and the portion(s) of the bone that should be resected to improve
the fit with the prosthetic may be shown in red.
[0065] In light of the foregoing, the method of assessing the
quality of cuts for a procedure operates as follows. For in-vivo
and in-vitro applications, a three dimensional model of a portion
of a patient may be generated using any of a variety of
three-dimensional digitizing, scanning and imaging techniques. The
surgeon then selects the element to be inserted or implanted into
the patient and the processor generates a model of the patient with
the location and orientation of the ideal cuts to the respective
portion(s) of the patient.
Programming Path for Surgical Robot
[0066] As discussed previously, the system provides feedback for a
surgeon during a surgical procedure to aid in guiding the path that
the surgeon should follow during a procedure. Additionally, it may
be desirable to provide the ability to easily define the path that
a robot should follow during a procedure.
[0067] Referring to FIGS. 1 and 12, a system for programming a
surgical robot 200 is illustrated. To program the robot, a doctor
performs a virtual procedure on a model of a portion of the
patient. The virtual procedure is then translated into a set of
instructions that the surgery robot follows during the actual
procedure on the patient.
[0068] The system for programming the robot includes a virtual
surgery computer, such as the pre-op computer 70 and a control
computer, such as the OR computer 80. The control computer
communicates with and controls the operation of the surgical robot
200. The virtual surgery computer is used to create the
instructions for the surgery robot.
[0069] In step 450, a virtual model is created for the portion of
the patient on which the procedure will be performed. As described
above, a virtual model can be created using a series of CT scans,
MRI scans, interpolating the data among the scans, using
statistical procedures, directly digitizing a portion of the
patient, or otherwise. The patient model is uploaded to the virtual
surgery computer and is displayed to the surgeon in step 455.
[0070] The virtual surgery computer includes one or more input
devices for inputting information into the computer. For instance,
the computer may include a keyboard 75 and one or more position
tracking devices 77 such a mouse or a stylus and pad.
[0071] Software on the virtual surgery computer allows the surgeon
to manipulate and perform a virtual procedure on the patient model.
Specifically, the software provides an interface so that the
surgeon can manipulate the patient model to view the patient model
from different angles and perspectives. For instance, the surgeon
can use the keyboard alone or in combination with the mouse to
manipulate the orientation of the patient model.
[0072] The system may also include the ability to virtually align
and place an element that is to be implanted during the actual
procedure. Further still, the location and amount of tissue to be
resected may be calculated and displayed on the patient model.
[0073] During many surgical procedures, an element is implanted
into the patient. For instance, during an orthopaedic procedure, a
prosthetic element is implanted into the patient to replace one or
more articular surfaces in a joint. One example is a total knee
replacement (TKR) in which surfaces of the knee joint are replaced
with a series of knee prosthetics. The procedure includes the
placement of a patellar prosthetic onto the patella, a femoral
prosthetic on the end of the femur and a tibial prosthetic on the
tibial plateau. During the placement of each prosthetic, a portion
of the corresponding bone is resected to accommodate the respective
prosthetic.
[0074] During the actual procedure, the bone to be resected is
determined by configuration of the prosthetics and the position and
orientation of the prosthetics relative to the corresponding
tissue. Accordingly, during the process of programming the surgical
robot, it is desirable to utilize models of the prosthetics.
Specifically, the virtual surgery computer may include three
dimensional models representing the size and shape of various
prosthetics.
[0075] To incorporate a model of a prosthetic into a virtual
procedure, the surgeon selects a prosthetic and the size for the
prosthetic. Typically, during an actual surgery, alignment jigs and
fixtures are used to identify the bone to be resected. Similarly,
during a virtual surgery the model is aligned to the bone (step
457). When performing a virtual surgery, the software may include
alignment tools that are configured to identify relevant criteria
on the tissue that is used to locate and align the virtual model of
the prosthetic. In other words, the virtual alignment tools may
operate to automatically align the model of the prosthetic based on
a characteristic of the patient model. The characteristic can be
automatically identified by the computer based on a set of
pre-established criteria for evaluating a patient model, or the
characteristic can be identified by the surgeon. After the relevant
characteristic is identified, the alignment tool in the software is
used to identify the location and orientation for the prosthetic
model. Alternatively, the surgeon may manually align the model of
the prosthetic onto the patient model based on the configuration of
the prosthetic and the configuration of the patient.
[0076] After the location and orientation of an implant is
determined, the computer may automatically determine the tissue to
be resected (step 458). Specifically, the amount of tissue to be
resected is determined based on the configuration of the prosthetic
as known from the model, and based on the orientation and location
of the prosthetic as determined during the alignment of the
prosthetic described above. By way of example, when implanting a
femoral prosthetic, the configuration of the prosthetic is known
from the data for the prosthetic model. Once the model of the
femoral prosthetic is aligned on the model of the patient, the
computer can evaluate the intersection of the prosthetic model and
the model of the patient's femur to determine the location and the
amount of the femur that should be resected to accommodate the
femoral prosthetic. This determination is then displayed on the
patient model to aid the surgeon in the virtual surgery. For
example, if the femur is displayed as a white solid object, the
bone to be resected may be displayed as a red portion of the
femur.
[0077] The software also includes onscreen tools that the surgeon
can control via one or more of the position tracking devices 75,
such as a surgical saw, a mouse or a pointing device. Further,
preferably the software provides a number of different tools that
the surgeon can select (step 460) during the virtual procedure. The
onscreen tool can be as simple as a pointing device that allows the
surgeon to trace a path along the patient model. The path
represents the path that the surgeon desires the surgical robot to
follow during the actual procedure. Further, the onscreen tools can
be representative of tools that will be used during the actual
procedure. For instance, the tools may include a cutting element,
such as a bone cutting saw.
[0078] After selecting the appropriate onscreen tool, the surgeon
manipulates the input device 77 to manipulate the onscreen tool
relative to the patient model (step 465). The surgeon can
manipulate both the position and the orientation of the onscreen
tool relative to the patient model. As the onscreen tool is moved
relative to the patient model, the software evaluates and displays
the result (step 470). For instance, if the onscreen tool is a saw
and the saw intersects the patient model, the software alters the
patient model to show a portion of the patient model cut and/or
removed.
[0079] Specifically, based on the coordinates provided by the input
device 77, the software determines the position and orientation of
the onscreen tool relative to the patient model. The software
determines what portions of the onscreen tool and patient model
intersect, and at what angle the tool intersects the patient model.
If the onscreen tool intersects the patient model, the software
determines the coordinates of the intersection and the result of
the intersection based on the tool selected. For example, if the
onscreen tool is a drill, the software will determine the size,
location, angle and depth of the hole based on the diameter of the
drill selected by the surgeon and the position of the drill
relative to the patient model. The result of the intersection
between the onscreen tool and the patient model is illustrated in
real time (step 470) so that the surgeon can see the result of the
virtual procedure as it is performed.
[0080] In this way, the surgeon can use a virtual surgical tool to
perform a virtual procedure and the virtual surgery computer will
display the progress of the procedure in real time. Further, if the
tissue to be resected is identified on the model, as described
above, the computer shows the removal of such tissue as it is
virtually resected. For instance, in the example in which the bone
to be resected is displayed in red, the computer will show the
removal of the red portion of the bone, as the surgeon virtually
operates on the bone.
[0081] The surgeon can reset the patient model to restart the
virtual procedure so that the surgeon can see the result of using
different paths (step 475). The surgeon can either re-set the
entire procedure or just one or more of the steps taken during the
virtual procedure. For instance, the surgeon can perform the
surgical procedure along a first path or series of paths, and then
perform the virtual surgery along a different path or series of
paths to determine which path is the optimum path to use for the
actual surgery. Additionally, since the surgical procedure will
likely include a plurality of paths (i.e. more than a single cut),
the surgeon can re-set a particular step rather than all of the
steps in a virtual procedure. Specifically, if the surgeon performs
a number of steps in a virtual procedure, the surgeon can re-set
each step in series to step back through the procedure to alter one
or more of the steps. For instance, after the seventh step the
surgeon may be unhappy with the result, so the surgeon may undo the
previous two steps. The software then resets the model so that it
displays the result of the patient's model after the first five
steps in the virtual procedure.
[0082] As described above, the surgeon performs a virtual procedure
of one or more steps by manipulating an input device to control the
path of one or more onscreen tool(s). After the surgeon is
satisfied with the result of the virtual procedure, the surgeon
verifies the virtual procedure to confirm that the virtual
procedure is to be used to create the instructions for the surgical
robot 200. The verification can be as simple as providing an input
indicating that the virtual procedure performed is to be used to
create the instructions for the surgical robot.
[0083] As described above, the virtual surgery computer monitors
the input of the input device during the virtual procedure. At the
same time, the computer records various information for each step
of the virtual procedure. Specifically, for each step, the computer
records the tool used, the path that the tool was displaced
relative to the patient model, and the orientation of the tool
relative to the patient model.
[0084] The path and orientation of the onscreen tool are determined
relative to a reference point on the patient model. The reference
point is used to correlate the patient model and the patient during
the surgical procedure. In other words, the path and orientation of
the onscreen tool for each step of a procedure is determined
relative to the reference point, and then the path and orientation
of the surgical robot are calculated to orient and displace the
surgical robot relative to the reference point.
[0085] Based on the data recorded for each step of the virtual
procedure, the computer calculates a series of instructions for the
surgical robot. The instructions are exported to a server that is
in communication with the control computer. The instruction set is
then uploaded to the control computer to be used to control the
surgical robot during a procedure.
[0086] To commence the actual surgical procedure, the position of
the surgical robot is correlated with the reference point on the
patient. After the position of the robot is correlated with the
reference point on the patient, the surgeon commences operation of
the surgical robot. The control computer controls the position and
orientation of the surgical robot in response to the instruction
set determined in step 485. In this way the movement of the tool on
the surgical robot parallels the movement of the onscreen tool as
manipulated by the surgeon during the virtual surgery.
Specifically, based on the instructions set, the control computer
controls the movement of the surgical robot tool, so that the
displacement path and orientation of the surgical robot tool
relative to the reference point is substantially similar to the
displacement path and orientation of the onscreen tool relative to
the reference point on the patient model. Further, the control
computer controls the surgical robot so that the surgical robot
follows the identical or substantially the same sequence of steps
that the surgeon took during the virtual surgery. Specifically, the
control computer controls the surgical robot so that the first step
taken by the surgeon is the first step taken by the surgical robot;
the second step taken by the surgeon during the virtual surgery is
the second step taken by the surgical robot, and so on. In this
way, the sequence of steps, along with the movement and orientation
of the surgical robot tool is the same as or substantially similar
to the sequence of steps, and the movement and orientation of the
onscreen tool used by the surgeon during the virtual procedure.
[0087] In the foregoing description, the system has been described
as including two separate computers connected with a server. The
advantage of such a configuration is that the virtual surgery
performed to program the surgical robot can be performed remotely
from the operating area. However, the actual configuration of the
system can vary. For instance, the virtual surgery computer can be
directly linked to the control computer, eliminating the need for a
server. Alternatively, rather than linking the two computers, data
from the virtual surgery computer can be exported to a storage
medium and then uploaded to the control computer. For instance, the
data, such as the instructions set can be exported to a optical
disk, such as a CD or other memory device, and the control computer
may include a device for reading the data from the storage medium.
Further still, it may be desirable to use a single computer for
both the virtual surgery and to control the surgical robot, thus
eliminating the need for two separate computers and a server. In
addition, although the surgical robot has been described as being
controlled by a separate computer, the robot may be controlled by
an integrated microprocessor that receives the operating
instructions and controls the robot, rather than a separate
computer such as a personal computer.
Detecting Tool Deflection
[0088] As described above, the position detection device 120 can be
used to detect and monitor the position of either a surgical tool
100 or a surgical robot 200. One issue in correctly navigating the
surgical tool or the robot is the need for an accurate assessment
of the position and orientation of the surgical tool or robot.
Specifically, although a number of markers 105 may be used to
identify the position of a tool, markers are typically not applied
to the tip of a tool, particularly if the tool is a cutting tool.
Instead, the position of the tool is determined and the position of
the cutting tip is calculated based on the known geometry of the
tool, and the presumption that the tool is a rigid element.
However, during use, the tool may deflect or deform so that the
actual position of the cutting tip may not correspond to the
presumed position of the cutting tip. Therefore, the correlation
between the actual tissue being cut and the virtual model do not
match. In other words, based on the data received from the position
detection device the OR computer 80 determines that a certain
portion of tissue is resected, however, due to tool deflection the
actual tissue resected may be different.
[0089] To accurately identify the position of a tool during a
procedure, the tool may include a sensor for detecting deflection
or deformation of the tool. For instance, referring to FIG. 2, a
surgical tool 100 is illustrated, having a cutting blade 102. The
surgical tool 100 reciprocates the cutting blade during operation.
A sensor in the form of a load-cell 104 included in the saw detects
the force and/or torque applied to the blade. Alternatively, a
piezoelectric sensor may be connected directly to the blade to
detect the force and/or torque applied to the blade. The measured
force or torque is used to predict the distance "d" that the blade
bends. Specifically, properties of the cutting blade 102 are
stored. Based on the predefined cutting tool properties and the
measured force or torque, the amount of bending is calculated. The
calculated amount of bending approximates the distance "d" and is
used as a compensation factor to adjust the position of the cutting
tool detected by the position detection device 120.
[0090] In the embodiment discussed above, the position of the
cutting tool is constantly calculated based on the measured
position of the cutting tool and the measured amount of force or
torque applied to the cutting tool. An alternative utilizes an
onboard processor to calculate the tool deflection and manipulate
the position detection element(s) on the cutting tool. In this way,
the position detection device 120 will detect the compensated
position of the cutting tool, which will reflect the actual
position and orientation of the deflected cutting tool.
[0091] Referring again to FIG. 2, the surgical tool 100 may include
a processor 106 operable to receive signals from the load cell 104
indicative of the force applied to the cutting blade.
[0092] Based on the data received from the load cell, the processor
106 calculates the deflection "d" of the tip of the cutting tool
102.
[0093] As shown in FIG. 2, the surgical tool 100 includes an
element for detecting the position of the surgical tool. For
instance, in the present instance, the surgical tool includes a
reference frame onto which a plurality of markers 105 are mounted.
As described previously, the position detection device 120 detects
the position of the markers to determine the location and
orientation of the surgical tool.
[0094] In a system in which the deflection compensation is
performed by either the position detection device or the OR
computer, the frame is typically rigidly mounted to the surgical
tool so that the position of the markers relative to the rest of
the tool is fixed. However, as shown in FIG. 2, the frame 107 may
be movably connected to the surgical tool 100. Although the freedom
of movement of the frame may be limited, preferably the frame is
connected to the surgical frame by a connection that provides at
least two degrees of freedom, such as a universal joint.
[0095] Connected to the frame 107 are a plurality of actuators or
deflectors 108 that control the position of the frame. The
actuators 108 are in electrical communication with the processor
106, and preferably the processor 106 independently controls the
operation of each actuator.
[0096] The processor 106 controls the operation of the various
deflectors 108 based on the signals received from the sensor 104.
Specifically, as described above, the processor 106 calculates the
deflection "d" of the tip of the cutting tool based on the signal
received from the sensor 104. Based on the calculated deflection,
the processor determines the appropriate compensation to the
position of the frame to compensate for the deflection of the
cutting tool 102. The processor then controls the operation of the
actuators 108 to re-position the frame. For instance, in the
example illustrated in FIG. 2, the cutting tool is deflected an
amount "d" in a clockwise direction. Accordingly, the actuators 108
reposition the frame 107 to displace the markers 105 an amount "d"
in a clockwise direction. The position detection device 120 then
detects the position of the surgical tool at the compensated
position so that no further calculations are necessary to monitor
the position of the deflected cutting tool.
[0097] By utilizing an on board deflection compensation, the system
can incorporate deflection compensation, while still allowing the
surgical tool to be used with a variety of commercially available
position detection devices without the need to modify the software
used by such devices.
[0098] Although the foregoing example describes the onboard
compensation feature as utilizing a plurality of actuators to
reposition a reference frame, the configuration of the compensation
elements may vary depending on the configuration of the position
detection elements used.
[0099] For instance, other position detection devices may be used
in the system, such as systems that include electromagnetic
sensors, ultrasound elements or accelerometers. When such elements
are utilized, the compensation features may either vary the
position of the element or it may vary the data provided by such
elements in response to the data received regarding the load on the
cutting tool.
Alignment Element for Surgical Tool
[0100] When performing a navigated freehand procedure as described
above, one of the issues is the time that a surgeon typically takes
to align a cut before starting the cut. Frequently this alignment
causes unnecessary delay. To limit the delay caused during the
alignment process, the surgical tool may includes an alignment
guide mounted on the surgical tool. The position of the alignment
guide 115 is known relative to the surgical tool, so that the
position detection device 120 can determine the position of the
alignment guide. Accordingly, using the virtual navigation, the
surgeon can watch the monitor 85 (or a screen mounted on the
instrument) to see the position of the blade relative to the target
point for the cut identified on the virtual model. When the tool is
properly aligned on screen, the tool is properly aligned on the
patient. The guide is the anchored to the patient to align the tool
for the cut.
[0101] Referring to FIG. 4, the alignment guide 115 is an elongated
element positioned adjacent the cutting tool 102. The forward end
of the alignment guide 115 is positioned so that the tip of the
alignment guide protrudes beyond the tip of the cutting tool. In
the present instance, the alignment guide 115 includes a plurality
of retractable pins or spikes 116 positioned at the end of the
guide. The pins 116 are configured to anchor the guide 115 into
bone. The alignment guide 115 further includes a recess for
receiving the pins 116 when the pins retract so that the pins do
not interfere with the cutting operation of the tool.
[0102] Although the alignment guide 115 can be configured in a
variety of shapes, in the present instance, the alignment guide is
an elongated flat bar positioned parallel to the cutting blade 102
and in close proximity to the cutting blade. The guide 115
preferably is more rigid than the cutting blade, and preferably is
substantially rigid relative to the cutting blade. In this way, the
alignment guide supports the cutting tool limiting the deflection
of the cutting blade toward the guide.
[0103] During a procedure, the alignment guide operates as follows.
As described above, the surgeon views the monitor to properly align
the surgical tool to perform the cut. After the surgical tool is
aligned, the surgical tool is anchored to the bone by driving the
tool toward the patient bone to anchor the pins 116 in the bone.
The surgical tool may include an internal hammering device to lock
the anchoring pins 116 to the bone when the alignment is correct,
or the surgical tool can simply include a contact portion, such as
an anvil 118 that can be hammered to drive the pins 116 into the
bone. As described below, during a cut, the guide 115 collapses.
Accordingly, to anchor the pins into the bone, the guide 115
includes a brake or a lock to lock the guide in an extended
position while the pins are anchored into the bone.
[0104] Once the guide 115 is anchored to the bone, the surgeon
starts the tool and the cutting blade 102 is driven into the bone.
The lock or brake on the guide is released to allow the guide to
collapse during a cut. Specifically, the guide 115 is configured so
that it can collapse or telescope as the saw is moved forward
during the procedure. In other words, the pins 116 remain in
engagement with the tissue (e.g. bone) and the guide 115 collapses
as the saw move forward relative to the pins. In this way, the pins
116 anchor the cutting blade 102 as the cutting blade progresses
through a cut.
[0105] As described above, the alignment guide includes a flat bar
and retractable pins. However, the configuration of the guide can
vary based on a number of criteria, including, but not limited to
design, friction and heat requirements, sterilization needs etc.
For instance, rather than being an elongated flat bar, the guide
may comprise a pair of elongated cylindrical rods spaced apart from
one another. The ends of the rods may be pointed to facilitate
anchoring the guide into the bone, as shown in FIG. 5.
Navigable Marker
[0106] As described previously, the OR computer 80 may display a
virtual model of the portion of the patient on which the procedure
is to be performed. Further still, the location of the patient may
be registered to correlate the position of the patient with the
virtual model. In previous descriptions, the virtual model of the
patient was utilized to guide the surgeon in manipulating the
surgical tool to perform the surgery. Alternatively, the virtual
model of the patient may be used to guide the surgeon in marking
the operation site. The marking can then be used alone or in
combination with the guided freehand system described above.
[0107] Referring to FIG. 13, a navigable marking pen 250 is
illustrated. The navigable marking pen 250 includes one or more
elements for detecting the position and orientation of the marker.
For instance, the marking pen may include a reference frame 257 and
a plurality of position markers 255 similar to the frame 107 and
position markers 105 described above in connection with the
surgical tool. The marking pen 250 can be guided by viewing the
display of the OR computer 80 as described above in connection with
operation of the surgical tool 100. The marking pen 250 is guided
to draw lines on the bone at the appropriate locations as
identified on the virtual model.
[0108] The method for using the navigable marking pen 250 operates
as follows. Prior to the procedure, a virtual model of the relevant
portion of the patient is created as discussed above. The surgeon
analyzes the virtual model to determine the procedure to be
performed and identifies the portion of the patient to be resected
or otherwise operated upon during the procedure. For instance, in
the instance of implanting a prosthetic device, a femoral
prosthetic may be implanted as previously described. The surgeon
selects the appropriate prosthetic and aligns a model of the
prosthetic over the operation site. Based on the model of the
prosthetic and the alignment, the Pre-op computer 70 may identify
the tissue to be resected during the procedure. Prior to the
procedure, the patient is registered as described previously, so
that the patient position corresponds to the virtual model. The OR
computer 80 displays the virtual model along with a model of the
navigable marking pen and an indication of the tissue to be
resected. As the surgeon manipulates the marking pen 250, the
position detection device 120 detects the movement of the marking
pen and provides data to the OR computer so that the model of the
marking pen moves on the screen relative to the patient model in
real time. Accordingly, the surgeon manipulates the marking pen so
that the model of the marking pen aligns with the portion of the
virtual model indicated for resection. The surgeon manipulates the
marking pen 250 so that the model of the marking pen traces the
area of the virtual model identified for resection or other
procedure (such as drilling). In this way, the virtual model
provides a guide for guiding the surgeon to mark the appropriate
areas on the patient on which the procedure is to be performed. The
surgeon may then simply perform the procedure freehand using the
markings on the patient as a guide or the surgeon may perform the
procedure using the markings and also using freehand navigation
assistance as described above.
[0109] FIG. 13 also illustrates another potential improvement, in
that the marking pen 250 may include a retractable pen that
retracts when the marking pen is not aligned with the proper area
on the patient. By retracting, it is much less likely that the
surgeon may erroneously mark an incorrect area.
[0110] As shown in FIG. 13, the marking pen 250 includes a hollow
housing 260 having a generally open forward end. A displaceable pen
275 is disposed within the hollow housing 260. The pen is
displaceable between an extended position and a retracted position.
In the extended position the tip of the pen extends from the
housing so that the tip of the pen can be used to mark a surface.
In the retracted position the pen is retracted into the housing so
that the forward tip of the pen is within the housing so that the
pen can not be used to mark a surface.
[0111] A spring 285 connected to the pen 275 biases the pen toward
the retracted position. An actuator 280, such as a solenoid is
operable to extend the pen forwardly against the bias of the
spring. Specifically, when the solenoid is energized, the solenoid
drives the pen to the extended position. When the solenoid is
de-energized, the spring 285 retracts the pen into the housing.
Alternatively, the solenoid can be configured to drive the pen in
both directions, i.e. the solenoid can drive the pen forwardly and
rearwardly as desired.
[0112] The marking pen 250 is in communication with the OR computer
80 to receive signals indicating whether the pen 275 should be
extended or retracted. The marking pen may include a wired
connection to the OR computer, however, in the present instance,
the OR computer 80 includes a transmitter, and the marking pen
includes a wireless receiver for receiving signals from the
computer. The marking pen 250 includes a processor 270 for
receiving the signals from the computer and controlling the
extension and retraction of the pen 275 in response to the signals.
Specifically, the processor 270 controls the operation of the
solenoid to selectively energize and de-energize the solenoid in
response to signals received from the OR computer.
[0113] The operation of the retractable marking pen 250 is similar
to the operation described above. However, the OR computer
correlates the data from the virtual model with the data regarding
the position of the marking pen. If the OR computer determines that
the marking pen is positioned over a portion of the patient that
should be marked, the computer transmits a signal to the marking
pen 250 indicating that the pen should be extended. The marking pen
receives the signal and the processor 270 controls the solenoid,
thereby energizing the solenoid to extend the pen tip 275. If the
OR computer determines that the marking pen is position over a
portion of the patient that is not to be marked, the computer
transmits a signal to the marking pen indicating that the pen
should be retracted and the processor control the solenoid to
retract the pen. Alternatively, the processor may be configured so
that the solenoid is energized only as long as the controller
receives a signal indicating that the pen should be extended. In
this way, the OR computer sends a signal to the marking pen as long
as the computer determines that the marking pen is over a portion
to be marked. As soon as the computer determines that the marker is
over an area that is not to be marked, the computer ceases sending
a signal to the marking pen. The processor then de-energizes the
solenoid to retract the pen in response to the lack of signal.
[0114] As can be seen from the foregoing, the marking pen 250 can
provide an accurate and efficient method for marking cut lines and
other marking lines for performing a procedure. Prior to the
procedure, the surgeon may utilize the guidance system to
manipulate the marking pen by aligning the model of the pen with
the area of the virtual model to be operated on. While the surgeon
maintains alignment of the virtual pen with the portions of the
model indicated as proper marking lines (such as the outline of a
prosthetic), the OR computer sends a signal to the marking pen
indicating that the pen element 275 should be extended. As the
surgeon maintains the virtual pen aligned on proper parts of the
virtual model, the marking pen 250 marks the patient. If the
surgeon manipulates the pen so that the virtual pen moves out of
alignment with the proper parts of the virtual model, the OR
computer sends a signal to the marking pen (or ceases sending a
signal to the pen as described above) and the pen tip 275 retracts
into the housing so that the pen stop marking the patient. In this
way, the surgeon controls the retraction of the pen by maintaining
alignment of the virtual pen with the portion or portions of the
model the were identified during the pre-operative analysis as
portions to be marked.
Tool Registration Head
[0115] An important step during navigated surgery is the accurate
registration of the surgical tools. If a tool is not properly
registered the navigation of the tool will be flawed leading to
errors during the procedure.
[0116] Referring to FIG. 14 a tool registration head 300 is
illustrated. The registration head 300 is configured to cooperate
with a plurality of tools 320 that are configured to be mounted in
a plurality of sockets in the head. The sockets are configured so
that each socket cooperates with a particular tool. In this way,
the system identifies the tool type in response to a determination
of the socket into which the tool is mounted. For instance, the
registration head 300 may include first 312, second 314 and third
sockets 316, each having a different configuration. A first tool is
configured to mate with the configuration of the first socket, a
second tool is configured to mate with the configuration of the
second socket and a third tool is configured to mate with the
configuration of the third socket. Each socket further includes a
sensor indicating whether a tool is registered in it or not. If the
sensor in the first socket indicates the presence of a tool, the
system determines that the first type of tool is mounted in the
registration head. Similarly, if the sensor in the second or third
socket detects the presence of a tool, the system identifies the
tool as being the second or third type accordingly.
[0117] Alternatively, rather than including a sensor in each slot,
the registration block may include a plurality of detection element
310, such as reflective spheres, as shown in FIG. 14. The location
of each slot relative to the detection elements is known.
Therefore, by inserting the surgical tool into the appropriate
registration slot, the position of the surgical tool relative to
the registration block is known. Based on this position data, the
processor is able to determine which registration slot the surgical
instruments was inserted into, thereby identifying the
instrument.
[0118] Additionally, as described above, the various registration
slots may vary depending on the type of instrument used, as well as
the size of the instrument. For instance, in FIG. 14, the
registration block include several holes of varying size 312a,b,b.
By inserting the instrument into hole 312a, the system detects that
the instrument is a pointer or drill bit or a diameter
corresponding to hole 312a. Similarly, slots 314a,b,c are used to
indicate that the instrument is a saw of a particular
thickness.
[0119] Further, the sockets 310 and the tools may also be
configured so that each tool will only mount in a particular
orientation. In other words, each tool fits into a particular
socket in a particular orientation. In this way, by simply
identifying which socket a tool is mounted in, the system can
determine the tool type and orientation.
[0120] The registration head is in communication with the OR
computer 80 or the position detection device 120 so that the
registration head can communicate signals to the system indicative
of the tool registered in the head. The system may maintain a data
file for each tool type indicating the profile and operating
parameters for each tool. In this way, when the system identifies
the tool registered in the head 300, the system has the relevant
data regarding the size, configuration etc. of the tool so that the
system can monitor the position of the tool accordingly.
Identifying Regions of Waste Material
[0121] As described previously, the present system 50 could be
utilized to perform guided freehand surgery in which a model of the
patient is provided, along with a model of the surgical tool and
the models can be used to guide the surgeon during the actual
procedure. For instance, the patient model may include a portion
identified as tissue to be resected. The system tracks the movement
of the surgical tool 100, so that when the surgeon moves the tool,
the system displays the movement of the tool in real time on the
monitor. In this way, the surgeon can align the tool with the
patient by aligning the model of the tool with the portion of the
patient model identified for resection. In this way, the surgeon
can follow the onscreen guidance to resect a portion of tissue.
[0122] When resecting a portion of a bone a surgeon may cut more
rapidly and aggressively when the cutting tool is relatively far
from the boundary of the area to be resected. As the surgeon
approaches the boundary of the resection area, the surgeon may slow
the pace of cutting to ensure that the resection remains within the
desired boundaries. To help the surgeon readily assess the
proximity to the resection boundary, the system may provide
indicators and warnings to the surgeon as the surgeon approaches
the boundary. Further still, the system may be configured to
control the operation of the surgical tool 100 in response to the
proximity of the tool to the resection boundary.
[0123] As described above, the system provides for the
pre-operative analysis of a patient model and the identification of
the tissue to be resected. After the portion of the tissue to be
resected is determined, the system may analyze the data for the
model and identify the boundary for the resection. The tissue to be
resected may then be identified with a plurality of colors based on
the relation to the resection boundary.
[0124] For instance, the portion of the tissue that is not to be
removed may be illustrated in red. A portion of the tissue that is
to be resected that is relatively close to the resection boundary
may be illustrated in yellow. The remainder of the tissue to be
resected may be illustrated in green. In this way, as the surgeon
views the model during a procedure the surgeon may cut rapidly and
aggressively while the system indicates the tool is operating on
tissue in the green zone. As the surgeon approaches the resection
boundary, the model illustrates the tool as operating on tissue in
the yellow zone. This serves as an indication to the surgeon to
proceed more slowly as the tool approaches the resection boundary.
In this way, the system provides a readily identifiable graphical
display that informs the surgeon of the proximity of the surgical
tool to a resection boundary. Similarly, the system can be used to
identify the proximity of the surgical tool to sensitive anatomical
structures, such as nerves, vessels, ligaments etc. The anatomical
structures can be illustrated in red and the tissue proximate the
structures can be identified in yellow as an indicator to the
surgeon that the cutting tool is getting close to the sensitive
structure.
[0125] In addition to providing a graphical indication of the
proximity to a resection boundary, the system may provide a
graphical and/or audible warning to the surgeon. For instance, as
the system detects the surgical tool approaching the area proximate
the resection boundary (i.e. the yellow zone), the system may
display a graphical warning on the monitor 85 in addition to
illustrating the surgical tool in a yellow zone of tissue on the
model. Alternatively or in addition to the graphical warning, the
system may provide an audible warning indicating that the cutting
tool is approaching the desired boundary. The system may provide
yet another warning in the event the cutting tool is detected at or
beyond the desired boundary. In other words, if the surgical tool
enters the red zone the system may provide a further warning.
[0126] The system may also be configured to control the operation
of the surgical tool in response to a determination of the position
of the surgical tool relative to the desired boundary.
Specifically, if the system determines that the tool is positioned
within the tissue to be resected that is not proximate the boundary
(i.e. in the green zone), the system may allow the surgical tool to
controlled as desired by the surgeon. If the system determines that
the tool is positioned within the tissue to be resected that is
proximate the boundary (i.e. the yellow zone), the system may
reduce or attenuate the operation of the surgical tool. For
instance, if the tool is a saw, and it enters the yellow zone, the
system may slow down the reciprocation or revolution of the saw as
it moves proximate the resection boundary. Further still, if the
system detects that the tool is positioned at the boundary or on
tissue that is not to be resected or operated on, the system may
control the surgical tool by completely stopping the tool. Although
the system may automatically control the operation of the surgical
tool, the system includes an override function that allows the
surgeon to override the control of the tool. In this way, if the
surgeon determines that a portion of tissue should be resected that
was not identified for resection during the pre-operative analysis,
the surgeon can override the system and resect the tissue during
the procedure.
[0127] Yet another feature provided by identifying operating
parameters for different areas of tissue is the ability to
automatically vary the view displayed on the monitor during a
procedure. For instance, when the system detects the surgical tool
in a first area of tissue, the monitor may display a first view,
whereas, when the system detects the tool in a second area of
tissue, the monitor may display a second view. Specifically, if the
system detects the surgical tool in the green zone portion of
tissue, the system may display a wide angle or low zoom view so
that the surgeon can view more of the area being operated on. As
the tool enters the yellow zone, the system may change the view to
a more magnified view so that the surgeon can see the details of
the cut more clearly as the tool approaches the resection boundary.
If the surgeon prefers different views than the ones automatically
presented by the system, the surgeon can manually select a
different view. Additionally, the system may query the surgeon as
to whether the selected view should be the default view for the
particular zone of tissue. If the surgeon responds in the
affirmative, the system changes the default view for the particular
user, so that the new view is displayed for the user when the
cutting tool enters the corresponding type of tissue. In this way,
the system can automatically change the view based on detected
characteristics of a procedure and user preferences.
[0128] Another feature that may assist in guide the surgeon during
a procedure relates to the representation of the tool of the
surgical instrument. For instance, in the situation of a cutting
tool, such as a saw, the cutting tool is a generally flat
rectangular element. If the plane of a cut is illustrated by a line
through a portion of tissue, it may be difficult to assess the
angle of the cutting blade to ensure that the cutting blade is
aligned with the plane of the appropriate cut. Accordingly, the
cutting blade may be illustrated as an oval on the display. The
shape of the cutting blade then depends on the angle of the cutting
blade relative to the proper plane. If the cutting blade is aligned
properly the cutting blade will look similar to a line. As the
cutting blade is twisted relative to the proper cutting plane, the
cutting blade appears more rounded and oval. In this way, the
variation between the angle of the cutting blade and the angle of
the proper cutting plane is readily apparent based on the ovality
of how the cutting tool appears on the display.
Registration Pointer with Surface Contact Detection
[0129] As previously described, when registering the position of
the patient prior to a procedure, a portion of the patient is
scanned to identify one or more anatomical landmarks or features.
Such features or landmarks are utilized to correlate the patient
position with the virtual model created for the patient. One method
for acquiring the registration data utilizes a navigational pointer
that the surgeon traces over portions of the patient. However, when
the surgeon is tracing the surface, the tip of the pointer may come
out of contact with the surface of the patient. This is
particularly true when tracing over soft tissue or when tracing
along curved surfaces. If the pointer is not in contact with the
surface of the relevant portion of the patient the resulting data
points will be erroneous.
[0130] To improve the accuracy of the data collected during
registration, the system may include a pointer that incorporates a
surface contact detection element. If the pointer is out of contact
with the surface of the relevant portion of the patient, the points
are ignored during the registration analysis.
[0131] Referring to FIG. 15 an improved registration pointer is
designated 350. The pointer is an elongated element having a tip
configured to contact the relevant portion of a patient. The
pointer 350 is operatively linked with the position detection
device 120. The operative link may be a wireless connection in
which the pointer includes a wireless transmitter. Alternatively,
the pointer may be connected directly to the detection device via a
cable.
[0132] The pointer includes a sensor 360 for detecting whether the
tip of the pointer is in engagement with the patient or whether the
tip of the pointer is spaced apart from the patient. One possible
sensor 360 is an impedance sensor. Alternatively, the sensor may be
a simple force transducer. The pointer 350 includes a circuit 365
for analyzing the signal from the sensor and determining whether
the pointer is in contact with the patient surface based on the
signal from the sensor. The data for the point or points in which
the pointer was out of contact with the patient surface are not
utilized during the registration process. Specifically, the pointer
circuit may identify valid and invalid data by various means,
including a first method in which the pointer communicates the
relevant data to the position detection device 120 via a wired or
wireless connection. Alternatively, the pointer circuit may control
the position tracking elements so that the pointer is out of view
of the position detection device 120 when the pointer 350 is out of
contact with the patient surface.
[0133] In the instance in which the pointer circuit communicates
directly with the position detection device, the pointer circuit
evaluates whether the pointer is in contact with the patient based
on the signal received from the sensor 360. If the circuit
determines that the pointer is out of contact, the circuit
communicates a signal to the position detection device 120
indicating that the data points are invalid. In this way, as long
as the pointer remains out of contact with the patient surface, the
position detection device receives a signal from the pointer
indicating that the points are invalid and should be ignored.
[0134] Alternatively, the pointer may control the position
detection elements to essentially make the pointer disappear from
view of the position detection device 120 when the pointer is out
of contact. Since the pointer is out of view when it is out of
contact with the patient, no data is collected while the pointer is
out of contact. The steps for rendering the position detection
elements out of view of the detector varies depend on the type of
detection element. For instance, as described previously, the
position detection device may operate in conjunction with passive
and active markers. An active marker is a marker that transmits an
infrared signal to the detection device and the position of the
marker is identified by triangulating the received signal.
Accordingly, to control the active marker(s), the pointer circuit
365 controls the active markers by turning off the active markers
so that they no longer emit an infrared signal when the pointer is
out of contact with the relevant portion of the patient. While the
emitter ceases emitting infrared light, the marker is hidden from
the position detection device 120 so that the registration points
are not detected.
[0135] If the markers on the pointer are passive elements, the
markers are detected by detecting the infrared light reflected back
to the position detection device 120. In order to hide such passive
markers the pointer circuit may be used to control one or more
elements including a displaceable opaque surface and an
electronically/chromatically actuated effect to disable the
infra-red reflectivity of the ball.
Automatic Selection of View
[0136] During a procedure, the surgeon is able to manipulate the
view of the patient model to view the model from any desired angle
or magnification. Furthermore, the system may be configured to
automatically select the appropriate view based on the status of
the procedure and information regarding the surgeon's
preferences.
[0137] As described above, the system is operable to track the
position of the surgical instrument 100 and correlate the position
of the tool relative to a virtual model of the patient.
Additionally, the virtual model may indicate the portions of the
patient that are to be operated on. For instance, the virtual model
may identify the boundaries of the tissue to be resected during a
procedure. The tissue to be resected may include a number of
portions along a number of planes.
[0138] When resecting the various portions it may be desirable to
modify the view of the virtual model displayed on the monitor. For
instance, when cutting along a first plane it may be desirable to
view the virtual model from a first perspective, and when cutting
along a second plane it may be desirable to view the virtual model
from a second perspective. Accordingly, the system tracks various
data regarding the status of a procedure, including, but not
limited to the following: the position of the surgical tool
relative to the tissue to be resected and the orientation of the
surgical tool relative to the tissue to be resected. Based on the
position and orientation of both the tissue and the surgical tool,
the system calculates which surface is about to be cut during the
procedure.
[0139] The system is pre-programmed so that certain views are shown
by default for certain cuts. For instance, returning to the example
of resecting a femur in preparation for a femoral prosthetic for a
TKR procedure, several surfaces are to be cut, as shown in FIG. 10.
Each surface may be best viewed from a different perspective during
the procedure. When cutting the anterior surface of the medial
condyle a first view may be desirable, whereas when cutting the
anterior surface of the lateral condyle a second view may be
desirable. Accordingly, the system sets a pre-defined first view
for viewing the virtual model when the anterior surface of a medial
condyle is resected. Similarly, default views can be defined for a
number of common resection procedures. When the system determines
the cut to be performed, the system determines the best match for
the cut and displays the default automatically without the
intervention of the surgeon.
[0140] Further, the system can be configured to account for the
preference of each user. Specifically, a surgeon may desire a
different view than the default view for a particular resection
step or cutting plane. The system allows the surgeon to override
the default selection and specify the view for a particular cut.
The system stores the information regarding the desired view for
the particular cut for the particular surgeon and uses the view as
the default view in the future when the system determines that a
similar cut is to be made. The system tracks the user preference
based on the user logged into the machine.
[0141] In addition to automatically changing views based on certain
pre-defined presumptions, the system can be programmed to identify
the particular views to be displayed during a procedure. For
instance, during the pre-op analysis of the patient's model, the
surgeon may identify the view to be displayed for each portion of
the procedure. For example, during the resection of the bone for a
TKR, the surgeon may identify the view to be displayed for each of
the different cuts to be made during a procedure. These preferences
can be saved to the profile for the user and used in other future
procedures, or the information can simply be used for the
particular procedure. As the procedure proceeds, the system tracks
the surgical tool, determines the surface that is going to be cut
and displays the virtual model using the view chosen for the
surface during the pre-op procedure.
[0142] Referring now to FIG. 3 another embodiment of a computer
aided system with a surgical instrument 500 is illustrated. The
surgical instrument 500 is operable to assist in automated surgery
in a surgical suite as discussed above in connection with the
surgical instrument 100 described above. For instance, as described
above, the system may include position detection device 120 that
operates to detect the position of the surgical instrument 500
relative to the patient. In the present instance, the position
detection device detects the position of one or more markers 505 on
the surgical instrument and one or more markers connected to the
patient. In addition to the aspects, the surgical instrument 500
incorporates a number of features on the instrument itself so that
the instrument can be used to perform a number of functions.
Additionally, the surgical instrument may incorporate wireless
communication with the OR computer 80.
[0143] Referring to FIG. 3 the surgical instrument 500 includes a
tool, such as a saw 510, a microcontroller 515 for monitoring and
controlling operation of the tool 510, and a wireless unit 520. The
instrument 500 also includes an antenna 525. The wireless unit 520
and antenna 525 allow the instrument to send data to the OR
computer 80 regarding multiple status parameters, such as blade
bending, saw speed and battery charge. In addition, the OR computer
80 includes a wireless unit 86, such as a bluetooth wireless
element, and an antenna 87. The wireless unit 86 and antenna 87
allow the OR computer to send and receive data wirelessly to and
from the surgical instrument 500.
[0144] As described previously, the OR computer may be used to
guide the surgeon's operation of the surgical tool during a
procedure. For instance, the system may track the position of the
surgical tool in real time and turn on or off the surgical tool
depending on whether the tool is in proper alignment. For instance,
if the system detects that the surgical tool is adjacent an area to
be resected, the system may send a signal wirelessly to the tool.
If the tool does not receive such a signal, the tool will not
operate. Specifically, the surgical tool may have a manual switch
that the surgeon can manually turn on to operate the tool. However,
the tool will only run if both the manual switch is switched to the
on position and if the tool also receives a signal indicating that
the tool is properly positioned to perform a procedure. If either
the surgeon switches the tool off or if the tool does not receive a
signal indicating that the tool is properly positioned, the tool
will not turn on for cutting.
[0145] As described above, the tool 500 may receive signals
wirelessly to control operation of the tool. In addition to signals
controlling the on/off function of the tool, signals may also be
used to control other operation of the tool. For instance, the tool
may receive signals that operate to control the speed of the tool.
For example, as described above, the system may track the position
of the tool, so that the system can track whether the tool is
adjacent a cutting boundary for a desired procedure. As the tool
approaches the boundary, the system may send a signal to the tool
indicating that the tool should be attenuated to reduce the speed
of the tool. The circuitry in the tool 500 then attenuates the
operation of the tool in response to the wireless signal.
[0146] As described above, the surgical tool 500 may be controlled
in response to wireless signals from the OR computer 80. In
addition, operation of the system may be controlled by signals from
the surgical tool, which in this instance are wireless signals. For
instance, the surgical tool may include various actuators, such as
buttons, a joystick or a mouse ball. The operation of such
actuators may be used as input signals to control operation of the
OR computer. For example, operation of a joystick on the surgical
tool 500 may send signals to the OR computer 80, causing the
graphics displayed on the display 85 to scroll in a particular
direction. Similarly, one or more buttons can be programmed to send
wireless signals to change the perspective or magnification of the
graphic being displayed.
[0147] In addition to including actuators, the surgical tool 500
may include a display 530 or view screen as shown in FIG. 16.
Specifically, as described above, the tool may include a wireless
connection for receiving data from the OR computer 80. The OR
computer may transmit graphics data to the tool so that the display
530 may display the same graphics as are displayed on the main OR
computer 80 display 85. Alternatively, the display 530 may display
an alternate view to the graphic being displayed on the OR computer
display 85. In this way, the display screen 530 may be used to
guide the surgeon during a procedure in the same way that the OR
computer display 85 may be used to guide the surgeon.
[0148] As previously discussed, preferably a pointer is provided
for identifying reference points on the patient. Although the
pointer has been described as a separate element, the pointer may
be integrated into the surgical tool. For instance, since the
configuration of the saw blade is known, the tip of the saw blade
can operate as a pointer. Alternatively, a dedicated pointer may be
incorporated onto the surgical tool. It may be desirable to
configure the pointer so that it can be extended and retracted as
necessary so that the pointer can be readily used, while not
interfering with the operation of the cutting tool during a
procedure.
[0149] The operation of the pointer element may operate in
conjunction with an actuator on the surgical tool. For instance,
the tool may include a button for indicating that the pointer is
positioned at a reference point. When the surgeon positions the
pointing element at a point to be registered, the surgeon
simultaneously presses the button, sending a signal to the OR
computer indicating that the point is to be registered as a
reference point. The OR computer detects the position of the
surgical tool as determined by the position detection device, and
stores the data regarding the location of the reference point. In
this way, the OR computer stores information regarding the position
of the surgical tool in response to actuation of the button on the
surgical tool.
Cutting/Filing Blade
[0150] Referring to FIGS. 18-19 an alternate cutting blade 102' is
illustrated. The cutting blade 102' has alternate surfaces on the
body of the blade. The first side A is smooth as with a
conventional blade; the opposite side B of the blade is formed with
a plurality of cutting surfaces to form a filing surface. The
smooth side is used against the useful (remaining) bone when pure
edge cutting is required. The blade is flipped (e.g. by turning the
oscillatory saw head 180 degrees) when cutting and filing (or
filing only) is required against the useful remaining bone. The
bide then acts as a navigated file but with a cutting edge as well.
The cutting edge/tip and filing surface features combine to make
the navigated saw more effective for advanced navigated freehand
bone cutting. The filing surface can act as a navigated testing
plane to measure alignment accuracy of the surface and refine it by
filing.
[0151] It will be recognized by those skilled in the art that
changes or modifications may be made to the above-described
embodiments without departing from the broad inventive concepts of
the invention. It should therefore be understood that this
invention is not limited to the particular embodiments described
herein, but is intended to include all changes and modifications
that are within the scope and spirit of the invention as set forth
in the claims.
* * * * *