CA2460119A1

CA2460119A1 - Graphical user interface for computer-assisted surgery

Info

Publication number: CA2460119A1
Application number: CA002460119A
Authority: CA
Inventors: Josiane Crampe; Franck Maras; Francois Poulin; Cynthia Reinert
Original assignee: Orthosoft ULC
Current assignee: Orthosoft ULC
Priority date: 2004-03-04
Filing date: 2004-03-04
Publication date: 2005-09-04
Also published as: WO2005084570A1; EP1720478A1; EP1720478A4

Abstract

A system and a method for performing a computer assisted surgery (CAS) uses an expert system driven graphical user interface (GUI) that displays a series of display pages that provide information on related to respective steps required to perform the surgery. The system displays virtual images of surgical instruments used during the surgery, overlaid on fluoroscopic images of the implant site to assist the surgical team during instrument calibration, and implant preparation and installation. The GUI presents the surgical team faith a succession of options that the surgical team responds to using affirmation and negation actions. These actions are associated with an icon presented in a same region of the display pages, and are annotated with text relevant to an immediately presented option, permitting a substantial portion of the CAS to be effected using a foot-operated input device.

Description

OS-49CA OR File No.9-15228-32CA

GRAPHICAL USER INTERFACE L'GR
CGMPUTER.-ASSIS~L'ED SURGERY
ICI.~FICFiE APFErTI3I
Not Applicable.
~ECf~iNICAI~ FIEhL) The present invention relates in general to computer--assisted surgery, and, in particular to a graphical user ~_nterface, method and system for facilitating an orthopedic surgical proc:eaare with guidance from an expert system.
BACKGRC3UND ~F ~.'FIE INL'E~1~I~ON
Orthopedics is a branch of mediwine concerned with diseases, injuries, and conditions of the musculoskeletal system. A large number of= orthopedic surgeries are performed each dad,. To be optimally successful and efficient an orthopedic surgery require, in addition to a professional surgical team, perfect instruments, imaging support for planning and performing the surgery, and prec_~se control of_- each step of the surgery. ~'hese requirements are especially important when performing an orthopedic surgery using implants (for example screws, such as pedicle screws used in spinal surgery) because a misplaced implant may cause sericus harm too th.e patient, and further may fail to achieve its desired function.
Currently, in some types of orthopedic surgery including spinal opera-Mans, a screw hole position is assessed by radiographic imaging and curette palpation. It is recommended that holes be palpated w~~_th a curette, or by setting an electrorayographic or fibroscopic probe, before OS-49CA OR File No.9-15228-32CA

- 2 --screw installation. Furthermore, confirmation of screw placement requires intraoperative radiographing. In some types of orthopedic surgery more than one screw is placed into a patient. The variety of types of orthopedic surgery requires different surgical instruments and implants in a plurality of sizes and types. A11 of t'n.is makes the fob of a surgical team mere complicated. Some techniques for surgical operat.iors employ a computerized surgical assistance system that uses orthogonal X-ray imaging of the part of the patient of interest in order to simolify the tasks of the su-yg~_cal team. As is known in the art, installation of pedicle screws, hip replacements, knee replacements, and various other. orthopedic, orthodontic and neurological procedures can be assisted using computer technology.
An example of a computerized surgical assistance system is described it U.S. Patent No. 6,450~978 entitled INTERACTIVE COMPUTER--ASSIS'fED SURCJ-rrC~AL~ SYSTEM AND
METHOD THEREOF, which issued to Brosseau et al. on September 17, 2002" Brosseau et a1_. describe a computer-assisted surgical system and method i.r_ which a computer includes t~-Free-dimensional models of anatomical str-uctures and a user interface including a position sensing system to register_ in real-time the relative ioositions of the anatomical structures of interest and of a surgical tool.
Interactions between the tool and the anatomical structure are displayed on a monitor using the three-dimensional models. Multi-view display, transparency display and use of cutting planes allow the surgeon to visualize the interaction between the tool and the anatomical structures any time during the surgical procedure. The system can also OS-49CA OR File No.9-15228-32CA

- 3 --predict the constraint on anatomical structures before surgery.
Many other computer-assisted surgery systems are known and widely used, especially systems that are particularly useful or explicitly adapted for use in orthopedic sur_gery~
An example is United States Patent Number 5,305~203, entitled COMPUTER-AIDED SURGERY 1-APPARATUS, which issued April 19, 1994 to Raab. Raab teaches a computer-aided surgical device for aiding a surgeon in positioning a su_rgica~ ir,str_ument (power or manual) when performing surgery on unexposed and exposed portions of a patient. A rudimentary graphical user interface provides geometric diagrams to assist a surceon in guiding a surgical instrument.
While all such systems provide a user interface, they depend on the expertise of the su:_geon to guide the surgical process ~ As is we~_1 known,, modern surgery is performed by skilled teams that cooperate to accomplish the task as accurately and efficiently as possible. However, current computer-a:asisted surgery syst:em~s lack an expert system core that is adapted to capitalize on the expertise of team members.
Therefore there exists a need for a computer-assisted surgery system with a graphical user interface that can be used by a surgical team to facilitate a surgical procedure using the expert system. The GUI preferably provides an interface that is simple to u.se~ and integrated with the expert system core.

OS-49CA 0~~ file X0.9-15228-32CA

- 4 -RY O~' ~I3E ~ NTION
It is thereforr~ an object of the :i.nvention to provide a computer-assisted surgery system with a graphical user interface (GUI) adapted to guide a surgical tear~~ through a surgical procedure. The GUI provides a=,n interface that is simple to use, and integrated ~rith the expert system core.
F3FtIE~' DE~CR~PT~O~d OP ~~3E InRAyNC3~
Further features and odvantage~ of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which:
FIG. 1 schematically illustrates a system for performing computer-assisted surgery (C:AS) that inclwdes a graphical user interface (GUI) in a::ccardance with the invention;
FIG. 2 is a flow chart illustrating principal steps of a method for guiding the surga_cal team. in. performing a CAS
procedure via a GUI;
FIG. 3 schematically i1_lustrates an organization of content of a main menu cf the GUT used for computer assisted surgery;
FIG. 4 is a schematic view of a maim menu display page in a GUI used for computer assisted surgery, in accordance with an embodiment of the inventioi2;
FIG. 5 is a schematic view of a display page in the GUI for guiding a surgical team during -the calibration of an instrument;
FIG. 6 is a schematic view of a second instance of the main menu display page shown in FIG. 4;

0S-49CA OIL File No,9-15228-32CA

- 5 -FIG. 7 is a schematic view of a disp lay page in the GUI for guiding the surgical team through acquisition of images of the patient;
FIG. 8 is a schematic view of a display page in the GUI for guiding a surgical team during the validation of an acquired image;
FIG. 9 is a schematic view of a c,.isplay page of the GUI for guiding a surgical team during the preparation of an implant site; and FTG. 10 is a schematic view of a display page of the GUI for guiding the surgical team through installation of an implant.
It should be noted th~a.t throughout the appended drawings, like features a-re identified by like reference numerals.
I7ETAI~E~3 DESCRI~'~I~N C3F'° ~."~IE ~I~ETS ENiSODIN~N''1' The invention provides a simplified user interface for guiding a surgical team through a computez:-assisted surgery (CAS) procedure driven by an expert system, FIG. 1 shows an exemplary embodiment of a system 100 for performing a CAS, in accordance with an embodiment of the invention. The system 100 includes a computer 102 in an operating room 108. The cozriputer 102 has a processor 104 for executing a CAS applicat ion and a display monitor 106. The display monitor 106 presents information to a surgical team 110 in a graphical user interface (GUI) 112. In particular, the display monitor 106 is a video display adapted to display images in real-time. The GUI 112 includes a plurality of display pages associated OS-49CA OR File No.9-152.28--32CA

- 6 -with respective steps required to perform the surgical procedure. Some of the visual display pages display virtual images of selected surgical instruments 118 used during the surgical procedure everlai_d on fluoroscopic images of a part of a patient 220 tha-c. is subject to the surgical procedure. A manual input dev~_ce is preferably connected to the computer 102 to pe-:rmit the surgical team 110 to input commands to 'she CAS program for advancing through the series of display pages of GUS 112, as each of the respective steps of the surgical procedure is successively completed. The manual in~out device may be a keypad 114 that is easi~.y sterilized and resistant to fluid contamination. As is known to the persons skilled in the art, the manual input devi cF', like the keypad, c:an be placed in a sterilized plast~i.c bag. A similarly adapted foot-operated input device 122 may also be connected to the computer 102. 'hhe foot-operated device 122 preferably includes two pedals, one associated with an affirmation action, and the other with a negation action. Likewise two keys of the keypad 114 are associated with respective affirmation and negation actions. Th.e surgical team 110 may choose to operate eitl~.er the keypad 114 or the foot-operated input de~lice 122, as required. The computer 102 may further be connected to a mouse or like user input device.
The computer 102 is connected t.o a tracking system that includes a biwocular video camera 116 for locating and tracking position, orientation and movement of the surgical instruments) 118 which are secured to instrument locator(s), as cail_-i be explained below in more detail.
An imaging system, such as a fluoroscope 117 (a well known X-ray imaging system), acquires oriented fluoroscopic OS-49CA O:R Fiie 10.9-15228-32CA
images of a part o.y a patient 120 that is subject to the surgical procedure. As will be understood b:y those slcilled in the art, other i_nac~ing systv~ms can also be used such as any one of CT-Scan, NiRI, PET~ ultrasound and Echography.
The images acquired by the fluoroscope 11'7 are provided to the computer 102, in accordance with nh~:~ invention. As many oriented fluoroscopic images as aye required for the surgical procedure are acquired. The fluoroscopic images are processed by the CAS to provide views of the part of the patient 120 that are aligned with and scaled to the tracking system. Respective fluoroscopic images are then displayed in corresponding image content fields of display pages, and provide a visual guide for the surgical team 110 in the preparation and installation of are implant, as will also be explained below in more detaiJ_. The computer 102 may also be connected to a date network which may be a data network such as the Internet 124 or a local area r;.etwork (hAN) for accessing a remote data source 126 that stores expert systems or application s externally of the operating room 108. Alternatively, thE~ expert system applications are stored in a memory of the computer 10'2.
The invention also provides a method for guiding the Surgl.Ca1 team 110 in performing a CAS procedure using the GUI 112. A general overview of the _rnethod is described with reference to a flow chart 150 shown in FIG. 2. The method provides the surgical_ team 1i0 with information related to respective steps required to perform the surgical procedure using the ~'~L7I 112. Virtual representations of selected surgical instruments (herein "virtual instruments") within a field of view of the traclcing system are overlaid on the images of the part of the patient 120 that is subject to the surgical procedure.
In addition, a series of display pages presented by the OS-49CA OR File No.9-15228-32CA
_ g GUI 112 guide the surgical team 110 through the CAS
procedure, as each of the r_e:>pective steps is completed.
One embodiment of the GUI 112 provides visual and audio information related to instrument calibration, patient imaging, implant site preparation, and implant installation.
The method starts (step 152) by placing the CAS
equipment 102 in the operating room :108. Patient data, surgery type, and other information is then entered into the computer 202 (step 15~). The surgical instruments 128 are then calibrated (step 156)> During the calibration stepP the surgical team 110 is prom~cted to identify a surgical instrument to be calibrated and to connect a three-dimensional instrument locator 1"_9 tc the identified instrument 118. In one embodiment, the instrument locator 119 is a light-reflect~_ve reference tool. i~hen the identified instrument 1.18 is secured t.o the instrument locator 119~ the instrument is moved into a field of view of the binocular video camera 11.6 of the tracking system, so that images of the instrument locator :L19 can be used to automatically calibrate the instrument.
The surgical team 110 is (step 158) prompted to effect the acquisition of one or more differently oriented fluoroscopic images of the part of the patient subject to the surgical procedure. The resulting fluoroscopic images are then verified (step 160). If an image is not satisfac.tory~ (i.e. there is unacceptable contrastP the orientation is incorrect etc.) the expert system returns to step 158 to permit a substitute image to be acquired.
Otherwise, the expert system advances to step 162, and the image is calibrated. If more images a re .required for the surgical procedure (as determined in step 164), the expert OS-49CA OP, Pile No.9-15228-32CA

system returns to step 158, Otherwise the expert system advances to step 166. Menu options may be provided to permit the surgical team 110 to transform images, for example by selecting options to rotate, change contrast or brightness, flip or restore the fluoroscopic image.
In step 166, the fluoroscopic images are validated by the surgical team 11C with the guidance of the expert system. The GUI 1i2 prompts the surgical team to place one of the calibrated instruments on a part of t=he patient that is subject to the surgical procedure, and to compare the actual location of the surgical instrument 118 with the virtual instrument superimposed on the r:_mage of the pa_r~ of the patient. If the alignment between the calibrated instrument and image of the virtual. instrument is not acceptable, the image is deleted and tr~e procedure returns to step 158 where another fluoroscopic Image is acquired.
Once the fluoroscopic images required for the procedure have been calibrated and validated, the surgical learn 110 is then guided through the pz:eparation of implant sites (step 168). The GU:~ 112 prompts the surgical team 110 to position a calibrated dril:L guide or an awl tip connected to a calibrated instrument handle (for example) on the part of t:~e patient where an implant is to be inserted. The sv~te preparation is facilitated by the images which display the fluoroscopic image or images of the part of the patient, and by the virtual instruments.
Preferably an axis of the virtual instrument is displayed to indicate an orientate on of the dri:Ll guide or awl tip, The alignment of the position and orientation of the virtual instrument and the fluoroscopic images of the patient permit the surgical team to monitor site preparation, which Generally involves drilling a hole to OS-~19CA 0:.~ File No.9-15228-32CA

prepare a bone tc; receive the implant. Planning the implant site to se'_ect a position and axis of orientation may be performed as taught in the r~bo~;re-referenced co-pending, co-assigned patent applicaticn. Furthermore, during the preparation of the implant site, the GUT 112 may display a depth gauge used t:o indicate t:o the surgical team 110 a distance of travel of a dri~.)_ bit. The surgical team naturally monitors the depth of the hole throughout the preparation of the implant. site 170, in. part using the .LO GUI 112 that dynamical:~y updates the Visual display to indicate to the surgical team 110 the distance of travel of the instrument as the 121StruZllent is used to prepare the implant site.
The GUI 112 then prompts the surgical team 110 to insert the implant (step 172). Th.e GUI 112 displays selections to permit the surgical team 110 to advance to an implant installation step, and there displays, in corresponding image content fields, the fluoroscopic images of the part of the patient that: were displayed during implant site preparation. The virtual instrument, and an image of the selected implant positioned and oriented with respect to the other elements in view (herein a "virtual implant") are overlas.d on the di:;played fluoroscopic images. The virt~.za1 path of the implant is computed by the CAS application by tracki ng a path of the instrument used to insert the implant into the prepared implant site.
After the implant is installed, a "snap shot" (screen image saved in a file on the computer hard drive) is generally acquired (step 1i4). Snap shots may also be acquired at other times during the procedure us:i_ng a predefined commandb. keypad 114 key, mouse selection, etc.
Fluoroscopic images may also be taken to document the position of the ~.mpiant (s) . If it i;_~ determined that OS-49CA 0:~ File No.9-:L5228-32CA

another implant is to be inserted at a site visible .in the fluoroscopic images (step 176), the expe.r_t system returns to step 1&8. If required, the surgica_ tears may return to step 158 to acqui-r_e fluoroscopic images (not shown on the flow diagram). The GUI 1i2 will prompt the surgical team to clear the image banks if the clamp has been displaced.
Otherwise, it is determined (step 178; whether surgery is required at another site that .requires repositioning of the vertebral clamp or other position reference tool. If so

7.0 the image bank is cleared ( step 180 ) , ar_~d another location is prepared for surgery (step 182). The procedure then returns to step 158 to acqui-r_e images of the next site.
Otherwise, the surgical team can quit the CAS application.
FIG. 3 illustrates content and selections available 7_5 from a main menu 204 of the GLJI 122, i~~~ accordance with an embodiment of the present invention. As shown in FIG. 3, the main menu 204 includes a plurality of selections that are organized thematically. The selections provide the surgical team 110 ~~aith access to the functionality of the 20 CAS system 100, which is augmented with display pages.
Some of the display pages (other tharu the main menu 204 display page) are also illustrated in FIG. 3.
In the embodiment illustrated in FIG. 3, the GUI 112 provides a main menu 204. It will be noted that the main 25 menu 204 is a display screen with a Uniform view that dynamically displays content and selections depending on selections made by the surgical team, and a state of the expert system. As such, selections are adaptively displayed by the main menu 204 30 The main menu 204 is accessed after patient :information, surgery type, and other ins=o~:~mation is entered in one or more preliminary pages 202. A patient to be OS-49CA OR. E'i1_e No.9-15228-32CA

operated on is identified, the Type of operation !in the illustrated embodirlent, a spinal surgical procedure) is specified and an identification of each member of the surgical team is recorded, alo~:zg with any ot=her documentary information required. The type of_ operation is used by the CAS to select an instance of an expert system to drive the GUI 112. Consequently, the type of operation determines a configuratior_ of the remainder of the GUI 112, whir_h may differ from the exemplary structure described with reference to FIG. 3.
The main menu 204 permits the swrgical team 110 to access three general categories of furActionality, namely:
an instrument calibration L:election 206 for accessing functionality related to a calibrati_orz of selected instruments to be used during the su_rgv.cal procedures a patient imaging se:~ection 208 for accessing functionality related to a~:,quiring, processing and validating fluoroscopic images of a part of the vatient; an implant preparation and installation selecticr~. 210 for accessing functionality related to implant site planning, implant site preparation and implant insta_~lation. A setup selection 212 is also proviced to permit the surgical team 110 to quit the CAS applicats.on, and reset the tracking system. Other selections may also be displayed by the main menu 204 to provio.e access i_o other desired functions of the CAS application suc.~.z as, for example, context-sensitive help. The sLtup category may be used for selecting an arrancrement of the patie:.n'~, tracking system, fluoroscope, etc. tn~ithin each category of functionality, the GUI 112 may i nclude as ma:Y~y d.ispla.y pages as requi red to enable effica.ent and intuitive access to the functionality of the CAS application.

OS-49CA Oil File No.9-15228-32CA

Each of the categories of functionality offered by the selections 206-222 is associated with a corresponding menu bar icon that is used to effect the se sections 206--2:12, as will be described further below with respect to two instances of the main menu 204 illustraced in FIGsa 4,6.
Chile the expert system guides the surgical team through the steps of t'r~e surgical prot:.ec~ure, at any time while the application is run~iing there may be one menu selection suggested by the expert system, one or more allowable but not elicited selection., and one or more displ aged but not-selectable option (s ) . T'he not-selectable options are displayed as not availabi.e by a grayed-out appearance. Fo_r example, at a fv-r_st :Lnst ante of the main menu 204, the in,.plant pre~oaration and installation 1.5 selection 210 is rot selectable and is grayed-out, as required instrurt~ents have no-~ been ~:~,al.ibrated, and the required fluoroscopic images have not yet been acquired, calibrated, and verified. Further indications (such as ~'Smlleys", a WlZo.ru., aSSlstant, etC. ) may be associated with the respects.ve selections 206-210 to indicate ~rhich steps have been successfully completed and/or are to be completed. The first step expected by j~.he expert system is the selection and calibration cf one or' more instruments to be used in the invention.
Activating the instrument cals_bration selection 206 in the main menu 204 updates a means of selections presented to the surgical team. In 'the =illustrated embodiment, f:hese selections includes widgets (selectable icons, buttons, menu options, etca) for selecting at least one of a list of instruments that may be of use in the surgical procedure for launching respective calibr.at.ion display pages used to guide the surgical. team through the calibration of the 0S-49CA O:ES ~'.ile No.9-15228-32CA

associated instrument. Specif_i.cally, a. U--handle (universal tool handle) selection 216 and a drill guide selection 218, which are useful fo_r orthopedic spinal surgery, are presented. If the U-handle selection 216 is activated, a calibrate U-handle display page 220, an ern'oodiment of which is schematically illustrated in FIG. 5, is displayed.
Similarly, if the drill guide selection 218 is activated, a calibrate drill guide display page 222 i.s displayed. As will be understood by those skilled :in the art, more or 1_0 different instruments rr.ay be required for other surgeries such as hip or knee replacements, for e:xampl.e .
Pr_eferablyr in accordance with t=he invention, activation of the U-handle selection 216 or the drill guide selection 218 is effected by an action widget. The action widget is preferably an affirmation ac~ion button that is consistently displayed in a11__ displa~° pages in a same position. The affirmation action button ry.'~s further associated with a respective pedal o= the foot-operated device 122, and a key on the keypad 1:L4. The affirmation action button is associated with tl~.e acceptance of a currently presented option by the expert system via the GUI 112.
The calibrate U-handle and calibrate drill guide display pages 220,222 preferab=iy include illustrations and instructions for demonstrating how to secure the instrument locator 119 to the instrument, and directions for placing the =nstrument within a field of view of the tracking system, as will be descried further J~elow with reference to FIG. 5. Once an instrument has been: calibrated, the expert system again displays inst~:~urnent cal~_bration selection 206 and suggests a next instrument. that is deemed necessary for the sv.~rgical procedure< Once all instruments OS-49CA C?=: File No.9-1_5228-32CA

required for the surgical procedure have been calibrated, the expert system raay present the main menu 204, with the patient imaging selection 208 high:Lighted to prompt selection. The surgical team may alternatively choose the instrument calibration selection 206, and calibrate an optional instrument, if desired.
The patient ,~maging selection 208 cf the main menu 204 is used to access functionality of the C~?S related t o the capturing and processing of images of a. surgical site. The patient imaging selection 208 provides an acquire images setup selection 22~:, a validate images selection 226, a transform images selection 228 and a clear image bank selection 230.
Activation of the acquire images setup selection 224 launches an acquire fluc;roscope image c!isplay page 232 that guides the surgica,. team in controlling an imaging system (such as the fluoroscoyoe', of the CAS system to acquire fluoroscopic images. ~n7hen the imaging system is ready; the surgical team is prompted to acquire a fluoroscopic image using the affs_-rmation action button. The acquired fluoroscopic image is ,displayed immediately to the surgical team in the image content field of the acquire fluoroscope image display page 232 so tr~.at it c:an be verified, to ensure that adequate resolution of the specific area of interest is achieved. An example of the acquire fluoroscope image display page 232, in accordance with the illustrated embodiment, is shown in F7:G. 7.. The acquired images are automatically calibrated by activation of an affirmation action button in accordance with an embodiment of the invention. P. calibrate fl_uorc>scc>pe image display page 234 showing progress of she calib-Nation procedure is lisplayed. The calibwated fluoroscopic images of the OS-49CA OR_ File No.9-1.5228-32CA

surgical site is scaled to match the calibrated instruments, and are aligned w?_th the tracking system.
After each f,-uor oscopic image is calibrated~ the patient imaging :5electicn of the main menu 204 is displayed. After_ a firsc set. of calibrated f1_uoroscopic images (in this example the fluorosc:oy,'_c images are a paired anterior-posterior (AP) image and ~:. lateral (LAT) image) is calibratedy the expert system suggests the validate images selection 226~ although the surgical team may elect to acquire further images.
If the validate images selection 226 is selected and the affirmation action button is act:Lvated~ a va:Lidate image display page 236 is launched. The validate image display page 236 displays instructions trzat enable the surgical team to Tralidate a fluoroscopic: image by comparing positions of a calibrated instrument on the part of the person subject to the procedureY with. a position of the corresponding virtual instrument on the fluoroscopic image.
In accordance with i~he illustrated embodimentP FIG. 8 shows an exemplary validate image display page 236. The surgical team~ following step-by-step i:~structions can validate the calibrated image to verify th~:t the fluov~_OSCOpIC image is correctly aligned and scaled ~rith the v_ri~ual instrument and the coordinates of the tracking system. After the surgical team has compared a calibrated image with the real points on the surgery .site, the surgical team can accept the calibrated image us~~ng the affirmation action button, or discard it using a negation action button, that is consistently present in all of the display pages. If the image is acce~otedn the image is stored in an image bank of a memory of the com}~wter 102. Converse.l.yF ;i_f the image is rejected, the image is deleted.

OS-49CA OR File No.g-1.5228-32CA
- 17 _ Once the fluoroscopic image is t=ither accepted or rejected, the expert system presents the main menu 204. T_f there are more images that require validation, the main menu 204 is presented with the patient imaging selection 208 selectable, ~.nd the validate images selecti.cn 226 suggested. If the required number of fluoroscopic images a-re not av~~ilable (:i.a. Borne have been deleted), the acquire images setup selecticn of the main menu 204 with the patient ~_maging selection 208 being suggested is displayed. Otherwise, the implant preparation and installation selection 210 is selects able while the implant site preparation selection 252 is suggested.
After a minimum required dumber of fluoroscopic images have been validated, the surgical team can select the implant preparation and instal:Lation seiecai on on the main menu 204. However, it is not until all calibrated images are validated, that. the expert system displays the main menu 204 suggesting the implant preparation and installation selectu_on 210. ~TOnetheless, the surgical team can return to the patient imaging selection 208, and. choose a transform images selection 228 which permits tre surgical team to modify images by selecting opt=ion;a to rotate an image 240, change a contrast 242 or a brightness 244 of the image, or restore a transformed image 24~. Upon completion of the transformation, t le surgical team ~'_s presented with the same transformation options, and the :~urgical team can select another flucroscapic image, and apply ore or more other such transformations. C~lhen the surgical team has completed the desired transformations, the main menu is selected. The main menu 204 with the implant preparation and installation selection 210 active i.s ~>resented and the implant site preparaticn 252 is suggested. (assuming a OS-49CA Oft ~'ile No.9-15228-32CA
1 g ._ sufficient number of fluoroscopic images have been calibrated and validated).
Whenever an image is calibrated, the surgical team may select from the main menu 204 under the patient imaging selection 208, a clear image bank selection 230 that displays a remove images display page 248. The remove images display page 248 enables the surgical team to delete selected images acquired for the surgical procedure. The CUI i12 preferably displays the images in the image bank to facilitate selection of fluoroscopic images to delete. A
remove all images selection on the remove images display page 248 is generally used to restart i:cnage acquisition.
When the required number of calibrated and validated fluoroscopic images are present, and the instruments to be used are calibrated, the surgical team is guided to select the implant site preparation selection 252, which is suggested by the main menu 2f4s The affirmation of the implant site preparation selection 252 iaunch.es a prepare implant site display page 254 u.hat guides the surgical team through the preparation of_ the implant cite" At this time, the implant installation selection 256 is not available, and is grayed-out.
Selection of the implant site preparation selection 252 displays the prepare irnp-iar~t site display page 254. The surgical instrument chosen to prepare the implant site is aut:omat:ically detected using the instrument locator 119. After the instrument enters the field of view of the tracking systerr~r a status of an icon representing the calibrated instrument is charged: When the surgical instrument enters a field of view of the acquired image, the corresponding virtual instrument is superimposed on the image in both image content fields, as shown in one OS-49CA OR File IVo.9-15228-32CA
1 g __ embodiment illustrated in FIi~. 9 > Y~lhen the site is prepared, the surgical team selects the main menu 204 and is returned to the implant preparatiot2 and installation selection, in which the suggested action is implant installation 256.
In one embodiment of the invention, a depth gauge may be used t o guide the drilling of an implant site. After an implant site is prepared to receive an implant, the surgical team may prepare another implant site or install the implant. When ready, the surgical team is presented with an install implant display page 258, after affirming the implant irastallation selection 256. The install implant display page 258, an exemplary embcdiment of which is illustrated in FIG. 10, guides the surgical team through a process of inserting the i:azplant. A select screw (or implant) size (or size and type) widget is provided to permit the surgical team to select one of a catalog of implants that is to be inserted at the implant site. The virtual instrument and a selected virtual implant are superimposed in real-time ovear the fluoroscopic images of the part of the patient 120, permitting a visual representation of the actual path of 'the installed implant and the instrument.
After the implant is installed, surgical records may be completed by acquiring images of the implant using the fluoroscope, for example, o.r_ a snap shot of the image presented on the display moni'~or 1_06.
When the surgical team s lects the setup selection 212 from the main menu 204, a reset tracking system selection 260, and a quit application selection 262 are presented. If the tracking system fails for one reason or another, the surgical team selects the reset tracking OS-49CA OR File No.9-15228-32CA

system selection 26G, which provides a set of options and display pages for troubleshooting and remediation of the tracking system. T~7hen the surgical team has completed its procedure the quit application. selectior_ 262 is used to exit the program.
D~~p~.ay Pale F~a.t Having described an organizational structure of the GUI 112 shown in FIG. 3, an embodiment of selected display pages of one implementation of the GU:I 112 is further described below, anal is schematically illustrated in r IGs . 4-10, in order to illut~trate ho~a the expert system driven GUI 112 provides an Pfficient: interface for the surgical team 210. The sequence of di.spl.ay pages followed during a surgical. procedure may vary, depending on the selections by the surgical team.
Each of the display pages in accordance with the illustrated embodiment is visually divided into a top part, a middle area, ar_ci a bottom part . The bottom part of the GUI 112 includes an action bar 300 that displays an affirmation action button 302 and a negation action button 304 (although any widget of equivalent effect could be used). A uniform view of the options presented to the surgical team by the expert system is maintained to simplify the interface with t:rie surgical -team. Rather than presenting a number of options to the surgical team 110, the action bar 300 provides for the affirmation, or negation of a current option presented to the surgical team, and a main menu button 306 for accessing the main menu display page 204 (two instances of which are shown in FIGS. 4,6). As the foot-operated input device 122 provides activation of the affirmation and negation action buttons 302~304, hands-free access to the functionality of OS-49CA OF F~..le No.9-15228-32CA

the CAS application is facilitated. As will be recognized by those skilled in the art, hands-free operation is important in many surgical procedures.
The action buttons (i.e. buttons on the action bar 300) are represented in a state that provides visual information about the accessibility oz the button. The effect of triggering the action button, and a state of accessibility of the action button, is generally dependant on selections made in the top part and middle area of the display page that presents the action button. As described above, if an action button is not accessible, it is grayed-out; if the action button has been activated, it is illustrated as a depressed buttons if the action button is a suggested action by the expert system, the action button is intermittently illuminated (i.e. 'flashing"'); otherwise, a normal view of the action button is 'presented, indicating that the action button can be selected even though it is not suggested. If the action button is deactivated, a mouse cursor cannot be used to select the action button, and a corresponding key on the keypad 114 is ineffectual.
An audio tone may be associated with an attempt to select a grayed-out button.
With reference to particu_Lar display pages (illustrated in FIGS. 4-10), these states are exhibited.
When the main menu 204 is displayed, the main menu button 206 is not accessible, and is accordingly grayed-out (FIGs. 4,6). Further, in the validate image display page 236 shown in FIG. 8 the main m.en.u button 206 is grayed-out to ensure that a currently selected fluoroscopic image is either validated or rejected, to prevent the fluoroscopic image from remaining in an ambiguous state.

OS-49CA 0~; File No.9-15228-32CA

The main menu button 206 is otherwise a~Gailable at each of the display pages illustrated.
On both illustrated instances of the main menu 204, the expert system suggests the selections highlighted (in the top parts and middle areas of the display pages) and accordingly the affirmation action buttons 302 on these two pages are flashing The negation action buttons 304 are also grayed-out as there is no negative action associated with the selection identified by the 'pop parts and middle areas of the display pages.
In the calibrate U-handle display page 220 shown in FIG. 5, both the affirmation and negation action buttons 302, 304 are grayed-out as the actions taken by the surgical team are on the instruments themselves. As the last step in the instrument. calibration procedure, the U-handle is placed within a field of view of the tracking system, which automaticali~_v' calibrates the surgical instrument. During this last step, a completion bar. is overlaid on the calibrate U-handle display page 220 and the negation action button 304 is disp7_ayed i.n the normal (ready fcr activation) state, and is annotated with text indicating that the calibration process will be canceled if the negation ar_tion button 304 is selected. Similarly the affirmation and negation action buttons 302,304 are grayed-out in FIG. 10, because the function of the illustrated install implant display page 258, is uo permit a visual of the insertion, and to permit the selection of the implant size and type; none of_ which requires the action buttons.
In FIGs. 7 and 8 both the affirmation and negation action buttons 302,304 are displayed in the ready state.
Further in FIG. 9 the negation action button 304 is in the ready state, whereas the affirmation action button 302 is OS-49CA OR File No.9-15228-32CA

not available. At this juncture, activation of the negation action button 304 deletes a selected fluoroscopic image.
It will further be noted ~rith referer_ce to FIGS . 4-10, that the affirmation action button 304 and negation action button 302 are ar~notat ed with text that indicates a response to a corresponding presented option whenever the action button is not in a deactivated state. Acco_rdzngly, in FIGS. 4,5 the affirmative action button 302 annotated with "accept" is associated with initiating a selected procedure step (specifically the calibration of the universal handle, and the acguisition of a fluoroscopic image, respectively). In FIG. 7 the aff.irma.tion action button 302 is annotated with the text ''Calibrate°', while the negation action button 304 is annotated with "Delete" a fluoroscopic image. The "Delete" annotation on the negation action button 304 is also present on the prepare implant site display page 254 and effects the same action.
The affirmative action button 302 presented on the validate image display page 236 shown in FIG. 8 is annotated with the text °'Accept", indicating sa.tisf_actory agreement between the virtual instrument with respect to the fluoroscopic image, and the actual instrument with respect to the part of the persora. The negation. action button 304 on the validate image display page 236 is annotated with "Reject°' and is a:Lso used to delete a selected fluoroscopic image on the basis that it is not in acceptable alignment with a calibrated instrument.
h3ain hierau Di~~ai~~ ~agc~ F°arat FIGS. 4,6 schematically illustrate two instances of an exemplary main menu display page 204 displayed by GUI 112 on the display monitor 106. The instance shown in FIG. 4 OS-49CA 0~ Fa.le No.9-15228-32CA

is consistent with an initia~> presentation of the main menu 204, displayed once the preliminary information about the suy~gery has been entered. In the instance shown in FIG. 4, the main rnen~,z 204 is presented once the expert system asserts 'that instrument calibration is complete.
In accordance ~~rith the illustrated embodiment, the top part of the main menu 204 displays a menu bar 310. The menu bar 310 includes four rr~enu bar icons 316-322 each representing a respective one of the categories of functionality shown in FIG. 3; name~i_y~ the instrument calibration selection 206 represented by an instrument calibration icon 3:~.6 that resembles the three dimensional instrument locator 1191 the patient imaging selection 208 represented by a patient imaging icon 328 resembling the fluoroscope 117; the implant preparation. and installation selection 210 represented bar an implant icon 320 that resembles a vertebra contains.ng an implant: and the setup selection 212 represented by a setup icon 322 that, in other embodiments is associated with the preliminary display pages 202. It will be noted that the three icons relevant to performing the surgical procedure (icons 316-320) are grouped together, whereas the setup icon 322 is visually separated. The menu bar 320 further includes a right and a left button 324a,324b (which could be replaced by any equivale.rzt widget) that is associated with a respective key on the keypad x.14 and indicates the keys that can be used to change the selected menu bar icon (or other vertically offset selection set in procedural display pages). The right and left buttons 324a,324b are preferably also selectable by the mouse, if such an input device is available.

OS-49CA OR Fa_le No.9-25228-32CA

A righlighted border around a selected menu bar icon (as shown in FIG. 4, the instrument calibration icon 316) indicates which of the categories of functionality is currently active. Grayed-out menu bar icons (like other widgets) indicate that the menu bar icon (such as implant icon 320, as schematically shown on both FIGS. 4,6; are not available for selection; in a manner similar to the action buttons. In accordance with the illustrated embodiment of the invention, when the main menu 209: is displayedp each time the right or -~eft button 324a,324b is selected a menu bar icon that is right-adjacent or left-adjacent to a currently selected menu bar icon becomes the selected merau bar icon, wherein right and 7_eft adjacer;.cy are determined by the visual order with the further specification that the setup icon 322 is left-adjacent to the instrument calibration icon 316, a_r~d reciprocal)y, the instrument calibration icon 316 is r~lght-adjacent to the setup icon 322. In accordance with some embodiments of the invention, the grayed-out icons are by-passed. For example, when an icon right-adjacent to the selected icon is not available, and therefore grayed-out, activation of the right button 324a does not bring about the selection of the grayed-out icon; but rather selects the menu bar icon that is right-adjacent tc the grayed-oat button, if that button is available. Alternatively,. grayed-out menu bar iccns can be selected, however no options are available for selection in a middle area of the main menu 204, and both affirmation and negation acta_on buttons 302,304 are grayed out and not avai~.ableg when a grayed-out menu bar icon is selected.
The middle area of the main menu 204 displays one or more selections associated with a currently selected menu bar icon. As the instrument calibration icon 316 is OS-49CA OR File No.9-15228-32CA

selected in the main menu 204 shown in FIG. 4, the middle area selections presented form a list of surgical instruments that may be used in the surgical operation identified during initial setup. As an organizational feature of the information displayed in the middle area, the selections are divided into tasks 334 and options 336.
The task selections (i..e. selections presented within a task field, such as the calibrate U-handle selection 216) are deemed mandatory by the expert system, unlike optional selections (i.e. selections presented within an option field, such as the drill guide selection 218) are optional.
It will be noted that the calibrate U--handle selection 216 is highlighted by a text -background color inversion, although any other highlighting scheme could be used, to indicate which of the selections e~ualifies the option presented to the surgical team. Accordingly, the action currently suggested by the expert system is the acceptance of the U-handle selection 216; which is presented when the instrument calibration icon 316 is active. The surgical team further has an option of choosing another selection from the task or option fields 334,336 using up or down buttons 342a,342b. Changing the highlighted selection in the middle area using the up and down buttons 342a,342b in relation to grayed-out selections is analogous to the operation of the right and left buttons 324a,324b. The up, down, right, and left buttons 34;?a,342b,324a,324b are embedded in lists, menus, etc. and are used for changing selections, menu options, etc. on different display pages of the GUI 112, permitting the effic,'_ent use of the keys on the keypad 114. As will be apparent to those skilled in the ar_t, any number of layouts that provide the above-described functicnality in a user friendly and accessible manner can also be used in embodiments of the invention.

OS-49CA OR File No.9-15228-32CA

The middle area of the main menu 204 shown in FIG. 6 displays selections associated with the patient imaging icon 318 that is currently selected. Specifically the task field includes the acquire images setup selection 224, and the validated images selection 226, the former of which is highlighted. zhe option field includes the transform images selection 228, and the clear image bank selection 230. As only the ac~~uire images selection 224 is in the ready state (and all others are grayed-out), the effect of the up and down buttons 342a,342b is null.
Pr~ced~x~ra~. Dis~L~.P~~ F~~~
Display pages 220, 232, 236, 254 and 258 shown in FIGS. 5,7,8,9, and 10, respectively, are termed "procedural°' display pages as they rea.ate to steps in the computer assisted surgical procedure. An crientation bar 350 is featured on the top part of the procedural display pages for providing information :relating to the current step in the CA.S 100. Specifically the orientation bar 350 includes a place for the menu bar icon that indicates the category of functionality accessed (shown in a top left-hand corner), and a brief text field 352 for identifying a current step in tha surgica l procedure, notifying the surgical team of ava,~.lable commands, etc.
Naturally the instrument calibration icon 316 is presented on the calibrate U-handle display page 220; the patient imaging icon 318 is presented on the acquire fluoroscope image display page 232 and the validate image display page 236; and th.e implant ~_con 320 is presented on the orientation bar 350 of the prepare implant site display page 254, and the install implant display page 258.
The orientation bar 350 further d:Lsplays a plurality of instrument icons 354. Specific instrument icons 354 are OS-49CA Ou File No.9-15228-32CA

identified as follo~~rs: tJ-handle instrument icon 354a (shown on procedural display pages 220,236,254, 258)8 C-arm instrument icon 354b (shown on acquire fluoroscope image display page 232)a clamp instrument icon 354c (shown in procedural display pages 232,236,254y 258)a and drill instrument icon 354d (shown on the prepare implant site display page 254). T:ne instrument icons 354 presented on a procedural display page indicate which of the calibrated instruments (or instruments in the process of being calibrated) are expected to be used in. the current step of the surgical procec:ure. These indicated instruments may be presented in either a normal view, indicating that the instrument associated with the instrument icon 354 is within the field of view of the tracking system, or in a grayed-out view to indicate that the associated ir_strument is not within the field of view of the tracking system.
For example, the drill instrument icon 354d on the prepare implant site display page 254 shown in. F.a.G. 9 is grayed-out to indicate that the drill guide is not within the field of view of the tracking system.
The middle area of t:he procedural display pages displays one or more content fields related to a step in the surgical procedure that is underway. For example, calibrate U-handle display page 220 presemts an illustrated guide 356 for securing the instrument locator 119 onto the universal handle, and placing the instrument locator 119 within the field of view of the tracking system.
The middle areas of each procedural display page that is displayed after a fluoroscopic image is acquired, preferably includes two image content fields: an anterior-posterior (A-P) image content field 358x, and a lateral OS-49CA OR File No.9-15228-32CA

(LAT) content field 358b, for displaying respective fluoroscopic images 359a,359b.
The fluoroscopic images 359a,359b are preferably X-ray images but alternative imaging (e.g. ultrasound) can be used for imaging the part of the patient. In accordance with the embodiment shown, a vertebra7_ clamp is in a view of the fluoroscopic images 359a,359b and is rigidly secured to the spine of the patient. The clamp is used to automatically calibrate the fluoroscopic images 359a,359b during the calibration step.
In accordance with the illustrated embodiment, a number of AP and hAT fluoroscopic images may be acquired.
Associated with each of the image content fields 358a,358b for which selection of the fluoroscopic image is possible 25 (i.e. procedural display pages 232,236,254) is an image selection field 360, which, in the illustrated embodiment includes a numeral that identifies the fluoroscopic image, and the up and down buttons ;s42a,342b. The up button 342a is associated with a fluoroscopic image that has an incrementally higher identifier numeral, and conversely, the down button 342b is associated with an image raving an incrementally lower identifier numeral. In alternative embodiments, other image identifiers, and widgets for selecting images by their identifiers, can be used to provide intuitive user interaction. If only one image is acquired for display in one image content field, as is the case of the A-P image content field 358a in the acquire fluoroscope image display page 232 shown in FIG. 7, the up and down buttons 342a,342b are grayed.-out.
The image content fields 358a,358b of the validate image display page 236, the prepare implant site display page 254, and the install implant display page 258 are OS-49CA Ou File No.9-15228-32CA

shown with overlaid virtual instruments 370. More specifically the awi tip of the U-handle is displayed over the fluoroscopic image 359b of the validate image display page 236, and over the fluoroscopic images 359a,359b in the prepare implant site display page 254. The virtual instrument associated with the U-handle, having an appropriate tip is shaven ~,aith a virtua7_ z.mplant 372 (which is a pedicle screw) on the install impl ant display page 258. In the illustrated embodiment of the prepare implant site display page 254, an axis 374 extends a predetermined distance from the center of the virtual instrument used to prepare the implant site, the axis being concentric with a major axis of the instrument. This axis 374 is useful for ensuring that the bored hole is well chosen. In some embodiments, the virtual implants remain displayed on the fluaroscopic images 359a,359b even after installation.
'!he patient imaging ican 318 is a.lsa displayed in each image content field. If the patient imaging icon 318 of an image content field is grayed-out(e.g. the LAT image content field 358b in FIG. 7), no image is available for viewing in the image content field, and a background 362 and image selection field 36() are grayed-out as well. Lf the patient imaging icon 318 contains an ellipsis, the image is in a pracess of being acquiv~ed (for example, see the A-P image com.ent field 358a show~~ in FIG. 7) . If the image is not yet validated, it is marked with an X, as shown in the LAT image content field 358b of FIG. 8, whereas the successfu:ily validated image content field is marked with a o~~.eck, as shown in the P.-P image content field 358b of the same figure.

OS-49CA O~ file No.9-152.28-32CA

The image conter_1t fields 358a,358b may further include backgrounds 3~2 that can be emphasized. or deemphasized to indicate which of the two image content fields is currently selected. In procedural display pages that permit the selection of fluoroscopic images, th.e surgical team is enabled to change the selectio-~ of the image content field using one of the r~_ght and left buttons 324a, 324b. If the A-P image content field is currently selected (as in FIG. 7) the right button 324a is included s.n the A-P image content field, for alternating selection to the LAT image content field. Symmetrically, a LAT image content field that is currently selected (as in FIGS. 8,9j includes the left button 324b, for selection the A-P image content field. As the LAT image content field 358b shown in FIG. 7 is associated witYi an empty image bank, the right button 324a is grayed-aut. Naturally the image selection field 360 of only the selected image content field is emphasized and includes the up and down buttons 342a, 342b.
It will be noted that the installation of the implant after the site has been prepared generally requires the same view of the implant site to be rendered because that image is most precisely calibrated with the drilled hole.
Accordingly no option for changing displayed images is presented to the surgical team (i.e. no image selection field 360;, during the implant installation procedure step, and backgrounds '?62 of both image content fields are highlighted.
Other fields as required are defined for respective purposes related to respective procedure steps. For example, an implant size field 364 that includes widgets for charging a selected impl~:nt size ;or alternatively size and type) is shown in FIG. 10. As is preferable, the implant size field 364 includes right and left OS-49CA Ok File No.9-15228-32CA

buttons 324a,324b. In alternate errlbodi.ments of the invention, the middle area of the instal7_ implant display page 258 includes a virtual path overla:~.d on each of the fluoroscopic images 359a,359b that are concentric with the implant sites, the path being computed with respect to the axis of the implant:, and an implant s=_ze . As the implant (e.g., a pedicle screw) is installed, tree virtual path of the implant is displayed in a contrasting color over the prepared implant site 510, for example" Concurrently, a 20 depth of the pedicl.e hole may be shown on a depth gauge as 'the insertion progresses. This permits the surgeon to monitor an axis of orientation and a depth of insertion of the implant.
Another examp7_e of a field used fo r a specific step in the surgical procedure is associated with the validate image display page 236. An illustrated description field 366 overlays the unselected image content field 358a in order to identify anatomical reference points used to verify the alignment of the calibrated instrument with the calibrated fluoroscopic. image (displa.yed in image content field 358b}. More specifically, the illustrated description field 358a displays arrows indicating points suggested by the expert system to be used to validate the fluoroscopic image. The surgical team places a calibrated instrument 118 on corresponding anatomical features of the patient. As the surgical team places the calibrated instrument (the U-handle with the awl tip, for example)r the CAS computes a position of the awl tip with respect to the image to be validated (fluoroscopic image 359b) and the GUI 112 displays a virtual image of v.he instrument on the fluoroscopic image 359b. The actual location of the calibrated instrument is then compared with the virtual representation ov the instrument on the fluoroscopic OS-49CA OR File No.9-25228-32CA

imacxe 359b. If the actual location of the calibrated instrument 118 at t:~e plurality of poieas on the part of the patient is indistinguishable from the position of the virtual representation of the instrument. on -the image to be validated, the image is validated and can be used for surgical purposes. The surgical team 220 accepts the validated image by pressing the affirmation action button 302. Alternatively, an audio tone may be sounded to indicate that the validated image has been saved.
The invention therefore provides an expert system driven graphical user interface that facilitates surgical procedures by guiding a surgical team through a surgical procedure, while providing critical information respecting the calibrations of the system, preparation of the implant site~ and placement of implants.
The embodiments) of the invention described above is(are) intended to be exemplary onlyr The scope of the invention is therefore intended to be :L.imited solely by the scope of the appen~ed claims.

Claims

I/WE CLAIM:

1. A graphical user interface (GUI) for guiding a surgical team through a surgical procedure, the GUI
comprising:
a series of display pages for providing information related to respective steps required to perform the surgical procedure, and for displaying to the surgical team representations of selected surgical instruments in a field of view of a tracking system overlaid on a fluoroscopic image of a subject of the procedure; and action widgets for permitting the surgical team to advance through the series of display pages as each of the respective steps is successfully completed.

2. A GUI as claimed in claim 1 wherein the action widgets comprise at least one action widget for responding to a presented option on each of the series of display pages, the presented option being presented by an expert system associated with the surgical procedure, in response to actions and selections by the surgical team.

3. A GUI as claimed in claim 2 wherein the action widgets include an affirmation and a negation action button, each of the buttons being presented in a same region of corresponding display pages, and wherein the action buttons are represented in a state that indicates one of: activation available for activation, suggested activation, and unavailable for activation.

4. A GUI as claimed in claim 3 wherein each of the action buttons in a state other than unavailable for activation is annotated by text associated with the presented option, and the action widgets further include a main menu button for accessing a main menu page.

5. A GUI as claimed in claim 3 wherein the series of display pages are organized in categories of functionality related to instrument calibration, patient imaging, implant site preparation, and implant installation.

6. A GUI as claimed in claim 5 wherein the display pages in the instrument calibration category comprise selections and content fields for permitting the surgical team to select surgical instruments, and calibrate the selected surgical instruments used to perform the surgical procedure.

7. A GUI as claimed in claim 6 wherein each of the display pages in any of: the instrument calibration, implant site preparation, and implant installation categories comprise a set of instrument icons representing respective calibrated instruments, the instrument icons being presented in a same part of the corresponding display pages, and wherein a state of each of the instrument icons indicates one of the following: the instrument is not used for a current procedure step, the instrument is outside the field of view, and the instrument is within the field of view.

8. A GUI as claimed in claim 7 wherein the display pages in the patient imaging category comprise selections and content fields for enabling the surgical team to:
control a fluoroscope to acquire images of a part of the patient; and validate the acquired images to ensure alignment using the calibrated instruments.

9. A GUI as claimed in claim 8 wherein the display pages in the patient imaging and implant site preparation categories further comprise:
at least two image content fields associated with respective incidences of the part of the patients;
an image identifier in each image content field; and ar image selection widget permitting the surgical team to select an image to be displayed in a selected image content field from among one or more banks of images.

10. A GUI as claimed in claim 9 wherein the at least two image content fields are also displayed in display pages in the implant installation category, and each image content field further comprises a patient imaging icon that is represented in a state indicating one of the following: that no image is available for an associated views that an image is being acquired; that an image is acquired but has not been validated; and that an image is validated

11. A method for guiding a surgical learn in performing a surgical procedure using a graphical user interface (GUI), the method comprising:

providing the surgical team with information related to respective procedure steps required to perform the surgical procedure using the GUI;
displaying to the surgical team representations of selected surgical instruments used during the surgical procedure, in alignment with a fluoroscopic image of a part of a patient that is subject to the surgical procedures and advancing through a series of display pages designed for the surgical procedure, as each of the respective procedure steps is successfully completed.

12. A method as claimed in claim 11 wherein advancing through a series of display pages comprises activating an action widget on each of the display pages for responding to a presented option, the presented option being presented by an expert system associated with the surgical procedure, in response to actions and selections by the surgical team via the GUI.

13. A method as claimed in claim 12 wherein the selecting an action widget comprises activating one of an affirmation and a negation action button, each of the buttons being presented in a same region of each of the display pages, and wherein a state of each of the action buttons indicates one of: activation, available for activation, suggested for activation, and not available for activation,

14. A method as claimed in claim 13 wherein activating one of an affirmation and a negation action button comprises selecting an action button that is in a state other than not available for activation, the action button being annotated with text associated with the presented options.

15. A method as claimed in claim 14 wherein providing the surgical team with information related to procedure steps involves providing content fields in display pages related to one of instrument calibration;
patient imaging; and implant preparation and installation.

16. The method as claimed in claim 15 wherein providing content fields in display pages related to instrument calibration prompts the surgical team to apply a sequence of procedures to calibrate a selected instrument, and wherein providing content fields in display pages related to patient imaging, implant site preparation, and implant installation include providing instrument icons located in a same position on the display pages and being presented in a state to indicate one of the following: the calibrated instrument is not required in a current procedure step; the calibrated instrument is within the field of view of the tracking system; and the calibrated instrument is outside of the field of view.

17. A method as claimed in claim 16 wherein providing content fields in display pages related to patient imaging comprises providing display pages that prompt the surgical team to acquire and validate fluoroscopic images at one or more substantially different incidences of the part of the patient, and wherein providing content fields in display pages related to patient imaging and implant site preparation, include presenting two image content fields for displaying corresponding fluoroscopic images of the part of the patient, each of the image content fields further comprising an image identifier of a currently displayed image and an image identifier widget permitting the surgical team to select another image identifier to be displayed in the image content field.

18. A system for performing a computer-assisted surgical procedure, the system comprising:
a computer including a video display supporting a graphical user interface (GUI) for guiding a surgical team in the performance of the surgical procedure, wherein the GUT includes a series of display pages for providing information related to respective steps required to perform the surgical procedure, and for displaying virtual images of selected surgical instruments within a field of view of a tracking system in relative alignment with a fluoroscopic image of a part of a patient subject to the surgical procedure;
the tracking system for tracking a location of the selected surgical instruments with respect to the part of the patient to permit overlaying of the virtual images of the selected surgical instruments on the oriented image of the part of the patient;
an imaging system for acquiring images of the part of the patient used to create the oriented images;
and means for permitting the surgical team to advance through the series of display pages as each of the respective steps is completed.

19. A system as claimed in claim 18 wherein the imaging system comprises one of a fluoroscope; MRI, CT-Scan, PET, ultrasound, and echography machine connected to the computer.

20. A system as claimed in claim 18 wherein the tracking system comprises:
a binocular visual system connected to the computer and a light-reflective reference tool connected to each of the selected surgical instruments that identifies an orientation and position of the surgical instrument.

21. A system as claimed in claim 18 further comprising a data network for connecting a remote data source to the computer.

22. A system as claimed in claim 18 wherein the means for permitting the surgical team to advance through the series of display pages comprises a manual input device connected to the computer.

23. A system as claimed in claim 18 wherein the means for permitting the surgical team to advance through the series of display pages comprises a foot-operated input device connected to the computer.

24. A system as claimed in claim 23 wherein the foot-operated input device comprises two pedals that are associated with affirmation and negation actions, respectively, the affirmation and negation actions constituting respective responses to an option presented by the display pages of the GUI, the option being presented by an expert system associated with the surgical procedure, in response to actions and selections by the surgical team.

25. A system as claimed in claim 24 wherein the affirmation and negation actions are associated with two corresponding keys of a manual input device, and two action widgets that are presented in a same position in each of the display pages.

26. A system as claimed in claim 25 wherein each of the two action widgets is a corresponding action button that is annotated with test associated with the presented option.