System and method for performing and evaluating a procedure

Disclosed is a method and system for performing a procedure. The system may include a navigation system and/or a surgical robot to be used to at least assist in the procedure. The system may assist in delineating objects and/or determining physical characteristics of subject portions. The system may assist in performing and/or a workflow of the procedure.

FIELD

The subject disclosure relates generally to a system and method for determining a position, including location and orientation, of a member in space relative to a subject.

BACKGROUND

Various procedures may be selected to remove, repair or replace portions of a subject. For example, in a human subject a portion of the human anatomy may be selected to be removed, repaired or replaced. During the procedure, a minimally or low invasive procedure may be selected. The low invasive procedure may limit direct viewing of a work area within the subject, but may decrease recovery time and/or discomfort to the subject.

A navigation system for various procedures, such as surgical procedures, assembling procedures, and the like, allow an instrument or object to be tracked. Tracking systems may include appropriate tracking systems, such as optical, acoustic, electro-magnetic (EM), etc. EM tracking or navigation systems include the AxiEM™ electro-magnetic navigation system sold by Medtronic Navigation, Inc., having a place of business in Louisville, Colo. The AxiEM™ electro-magnetic navigation system may include a plurality of coils that are used to generate an electro-magnetic field that is sensed by a tracking device, which may be the sensor coil, to allow a navigation system, such as a StealthStation® surgical navigation system, to be used to track and/or illustrate a tracked position of an instrument. Optical tracking systems include those such as the StealthStation® navigation system. The optical tracking system includes a set of cameras with a field of vision to triangulate a position of the instrument.

SUMMARY

A tracking device connected to an instrument is generally required to allow tracking and navigation of the instrument. The instrument, therefore, is generally specific to a tracking or navigation system. Disclosed is a system configured to determine the position of the tracked instrument and compare it to a predetermined volume or boundary. Generally, the tracked position may be used to indicate the relative position of the instrument to the predetermined areas and volume.

A system for performing a procedure is disclosed. The procedure may also be performed on a living subject such as an animal, human, or other selected patient. The procedure may include any appropriate type of procedure, such as one being performed on an inanimate object (e.g. an enclosed structure, airframe, chassis, etc.). Nevertheless, the procedure may be performed using a navigation system where a tracking system is able to track a selected one or more items.

A navigation system may be used to navigate an instrument relative to a subject during a selected portion of a procedure. In various embodiments, the procedure may include a procedure on a spine such as a decompression, spinal fusion (i.e. two or more vertebrae are connected together with a selected implant system or assembly) and/or discectomy. During a decompression a tissue, such as bone, removal instrument may be moved relative to a portion of the spine. The instrument may be tracked to allow a determination of the position of the instrument. The determined position may be illustrated along with or in the alternative to a relative position to predetermined volumes.

DETAILED DESCRIPTION

With initial reference toFIG. 1, a navigation system10is illustrated. The navigation system10may be used for various purposes or procedures by one or more users, such as a user12. The navigation system10may be used to determine or track a position of an instrument16in a volume. Exemplary instruments and systems includes those disclosed in U.S. Pat. No. 7,542,791, issued Jun. 2, 2009, incorporated herein by reference.

The position of the instrument may include both a three dimensional X,Y,Z location and orientation. Orientation may include one or more degree of freedom, such as three degrees of freedom. It is understood, however, that any appropriate degree of freedom position information, such as up to or less than six-degree of freedom position information, may be determined and/or presented to the user12.

Tracking the position of the instrument16may assist the user12in determining a position of the instrument16, even if the instrument16is not directly viewable by the user12. Various procedures may block the view of the user12, such as performing a repair or assembling an inanimate system, such as a robotic system, assembling portions of an airframe or an automobile, or the like. Various other procedures may include a surgical procedure, such as performing a spinal procedure, neurological procedure, positioning a deep brain simulation probe, or other surgical procedures on a living subject. In various embodiments, for example, the living subject may be a human subject20and the procedure may be performed on the human subject20.

It is understood, however, that the instrument16may be tracked and/or navigated relative to any subject for any appropriate procedure. Tracking or navigating an instrument for a procedure, such as a surgical procedure, on a human or living subject is merely exemplary. The tracked instrument16, tracked with a selected tracking system, as discussed herein, allows the position of the instrument to be determined. The determined position of the instrument16may also be compared to predetermined selected areas or volumes.

Nevertheless, in various embodiments, the surgical navigation system10, as discussed further herein, may incorporate various portions or systems, such as those disclosed in U.S. Pat. Nos. RE44,305; 7,697,972; 8,644,907; and 8,842,893; and U.S. Pat. App. Pub. No. 2004/0199072, all incorporated herein by reference. Various components that may be used with or as a component of the surgical navigation system10may include an imaging system24that is operable to image the subject20, such as an O-Arm® imaging system, magnetic resonance imaging (MRI) system, computed tomography system, etc. A subject support26may be used to support or hold the subject20during imaging and/or during a procedure. The same or different supports may be used for different portions of a procedure. A surgical robotic system25, as illustrated inFIG. 1A, may also be provided to assist in guiding or moving an instrument. Surgical robots include the Mazor X™ robotic guidance system sold by Medtronic, Inc. having a place of business in Minnesota, USA.

In various embodiments, the imaging system24may include a source24s. The source24smay emit and/or generate X-rays. The X-rays may form a cone24c, such as in a cone beam, that impinge on the subject20. Some of the X-rays pass though and some are attenuated by the subject20. The imaging system24may further include a detector24dto detect the X-rays that are not completely attenuated, or blocked, by the subject20. Thus, the image data may include X-ray image data. Further, the image data may be two-dimensional (2D) image data.

Image data may be acquired, such as with one or more of the imaging systems discussed above, during a surgical procedure or acquired prior to a surgical procedure for displaying an image30on a display device32. In various embodiments, the acquired image data may also be used to form or reconstruct selected types of image data, such as three-dimensional volumes, even if the image data is 2D image data.

The trackable instrument16may be tracked in a trackable volume or a navigational volume by one or more tracking systems. Tracking systems may include one or more tracking systems that operate in an identical manner or more and/or different manner or mode. For example, the tracking system may include an electro-magnetic (EM) localizer40, as illustrated inFIG. 1. In various embodiments, it is understood by one skilled in the art, that other appropriate tracking systems may be used including optical, radar, ultrasonic, etc. For example, an optical localizer82may be used to track the instrument16.

The discussion herein of the EM localizer40and tracking system is merely exemplary of tracking systems operable with the navigation system10. The position of the instrument16may be tracked in the tracking volume relative to the subject20. The position, or selected portion of the instrument16, may then be illustrated as a graphical representation, also referred to as an icon,16iwith the display device32. In various embodiments, the icon16imay be superimposed on the image30and/or adjacent to the image30. As discussed herein, the navigation system10may incorporate the display device32and operate to render the image30from selected image data, display the image30, determine the position of the instrument16, determine the position of the icon16i, etc.

With reference toFIG. 1, the EM localizer40is operable to generate electro-magnetic fields with a transmitting coil array (TCA)42which is incorporated into the localizer40. The TCA42may include one or more coil groupings or arrays. In various embodiments, more than one group is included and each of the groupings may include three coils, also referred to as trios or triplets. The coils may be powered to generate or form an electro-magnetic field by driving current through the coils of the coil groupings. As the current is driven through the coils, the electro-magnetic fields generated will extend away from the coils42and form a navigation domain or volume50, such as encompassing all or a portion of a head20h, spinal vertebrae20v, or other appropriate portion. The coils may be powered through a TCA controller and/or power supply52. It is understood, however, that more than one of the EM localizers40may be provided and each may be placed at different and selected locations.

The navigation domain or volume50generally defines a navigation space or patient space. As is generally understood in the art, the instrument16, such as a probe, may be tracked in the navigation space that is defined by a navigation domain relative to a patient or subject20with an instrument tracking device56. For example, the instrument16may be freely moveable, such as by the user12or by and/or with a surgical robot, relative to a dynamic reference frame (DRF) or patient reference frame tracker60that is fixed relative to the subject20. Both the tracking devices56,60may include tracking portions that are tracked with appropriate tracking systems, such as sensing coils (e.g. conductive material formed or placed in a coil) that senses and are used to measure a magnetic field strength, optical reflectors, ultrasonic emitters, etc. Due to the tracking device56connected or associated with the instrument16, relative to the DRF60, the navigation system10may be used to determine the position of the instrument16relative to the DRF60.

The navigation volume or patient space may be registered to an image space defined by the image30of the subject20and the icon16irepresenting the instrument16may be illustrated at a navigated (e.g. determined) and tracked position with the display device32, such as superimposed on the image30. Registration of the patient space to the image space and determining a position of a tracking device, such as with the tracking device56, relative to a DRF, such as the DRF60, may be performed as generally known in the art, including as disclosed in U.S. Pat. Nos. RE44,305; 7,697,972; 8,644,907; and 8,842,893; and U.S. Pat. App. Pub. No. 2004/0199072, all incorporated herein by reference.

The navigation system10may further include and or be in communication with a navigation processor system66. The navigation processor system66may include connections to the display device32, the TCA40, the TCA controller52, and other portions and/or connections thereto. For example, a wire connection may be provided between the TCA controller52and a navigation processing unit70. It is understood that the navigation processing unit70may include one or more processors of various types (e.g. general purpose processors executing accessed instructions and/or specific processors (e.g. ASIC)). Further, the navigation processor system66may have one or more user control inputs, such as a keyboard72(or others including a touch capacitive display, pen input, mouse, etc.), and/or have additional inputs such as from communication with one or more memory systems74, either integrated or via a communication system. The navigation processor system66may, according to various embodiments include those disclosed in U.S. Pat. Nos. RE44,305; 7,697,972; 8,644,907; and 8,842,893; and U.S. Pat. App. Pub. No. 2004/0199072, all incorporated herein by reference, or may also include the commercially available StealthStation® or Fusion™ surgical navigation systems sold by Medtronic Navigation, Inc. having a place of business in Louisville, Colo.

Tracking information, including information regarding the magnetic fields sensed with the tracking devices56,60, may be delivered via a communication system, such as the TCA controller, which also may be a tracking device controller52, to the navigation processor system66including the navigation processor70. Thus, the tracked position of the instrument16may be illustrated as the icon16irelative to the image30. Various other memory and processing systems may also be provided with and/or in communication with the processor system66, including the memory system72that is in communication with the navigation processor70and/or an imaging processing unit76.

The image processing unit76may be incorporated into the imaging system24, such as the O-Arm® imaging system, as discussed above. The imaging system24may, therefore, including the various portions such as a source and a x-ray detector that are moveable within a gantry78. The imaging system24may also be tracked with a tracking device80. It is understood, however, that the imaging system24need not be present while tracking the tracking devices, including the instrument tracking device56. Also, the imaging system24may be any appropriate imaging system including a MRI, CT, etc.

In various embodiments, the tracking system may include an optical localizer82. The optical localizer82may include one or more cameras that view or have a field of view that defines or encompasses the navigation volume50. The optical localizer82may receive light (e.g. infrared or ultraviolet) input to determine a position or track the tracking device, such as the instrument tracking device56. For example, at least two cameras at a fixed position relative to one another may view both the tracking device56of the instrument16and the DRF60on the patient20. Due to registration, the tracking system and the navigation system10may then determine the position of the instrument16(including at least a portion thereof) relative to the subject20. Generally, the position may be triangulated using the view of the volume50. It is understood that the optical localizer82may be used in conjunction with and/or alternatively to the EM localizer40for tracking the instrument16and also may have a communication line83with the navigation processor system66.

Information from all of the tracking devices may be communicated to the navigation processor70for determining a position of the tracked portions relative to each other and/or for localizing the instrument16relative to the image30. The processor70may execute instructions or be designed to analyze the incoming navigation signals to determine the position of the instrument16, as is generally understood in the art as discussed above. The determined position of the instrument16, however, may be displayed with the display device32in various manners and with various indications, as discussed herein. The imaging system24may be used to acquire image data to generate or produce the image30of the subject20. It is understood, however, that other appropriate imaging systems may also be used. The TCA controller52may be used to operate and power the EM localizer40, as discussed above.

The image30that is displayed with the display device32may be based upon image data that is acquired of the subject20in various manners. For example, the imaging system24may be used to acquire image data that is used to generate the image30. It is understood, however, that other appropriate imaging systems may be used to generate the image30using image data acquired with the selected imaging system. Imaging systems may include magnetic resonance imagers, computed tomography imagers, and other appropriate imaging systems. Further the image data acquired may be two dimensional or three dimensional data and may have a time varying component, such as imaging the patient during a heart rhythm and/or breathing cycle.

In various embodiments, the image data is a 2D image data that is generated with a cone beam. The cone beam that is used to generate the 2D image data may be part of an imaging system, such as the O-Arm® imaging system. The 2D image data may then be used to reconstruct a 3D image or model of the imaged subject, such as the patient20. The reconstructed 3D image and/or an image based on the 2D image data may be displayed. Thus, it is understood by one skilled in the art that the image30may be generated using the selected image data.

Further, the icon16i, determined as a tracked position of the instrument16, may be displayed on the display device32relative to the image30. In addition, the image30may be segmented, for various purposes, including those discussed further herein. Segmentation of the image30may be used to determine and/or delineate objects or portions in the image. In various embodiments, the delineation may be used to identify boundaries of various portions within the image30, such as boundaries of one or more structures of the patient that is imaged, such as the vertebrae20v. Accordingly, the image30may include an image of one or more of the vertebrae20v, such as a first vertebra20viand a second vertebra20vii. In various embodiments, the delineation may be represented, such as with selected icons, such as an icon20vi′or a second icon20vii′. The boundaries20vi′,20vii′may be determined in an appropriate manner and for various purposes, as also discussed further herein. Selected anatomical portions may include displaying a disc between vertebrae and or determining that a disc is between determined vertebrae. For example, in various imaging modalities, soft tissue of a disc may not be easily or directly viewable, while the bone of the vertebrae is easily viewed by the user12. With continuing reference toFIG. 1, the subject20may include a plurality of vertebrae, such as a first vertebra20v1and a second vertebra20v2. The vertebrae20vmay be surrounded or covered by soft tissue, such as a dermis, muscle, nerves, spinal cord and the like. In performing selected procedures, such as in a spinal fusion, discectomy, or other procedures, a small incision89may be made. A small incision may allow for a substantially minimal or low invasive procedure. For example, the incision may generally be about 1 millimeter (mm) to about 3 centimeters (cm) in length. Generally the incision allows access for instruments, such as the instrument16to a selected area while minimizing the incision size, which may also limit the view of the user12of the area where a procedure is occurring. In various procedures, such as in a spinal fusion, spinal decompression, or the like, material may be removed or impinged with the instrument16. For example, portions of one or more vertebrae may be removed, such as the vertebrae20v1and20v2. The two vertebrae may be any appropriate vertebrae, such as a third lumbar vertebra (L3) and a fourth lumbar vertebra (L4).

As illustrated inFIG. 1, the image30may include the vertebrae of the subject, along with other tissue of the subject20. As discussed further herein, an illustration of the vertebrae may include the image acquired with the imaging system24, or any appropriate imaging system, or a selected reconstruction thereof, such as a three-dimensional reconstruction.

In various embodiments, the imaging system24, or any appropriate imaging system, may include an image processing unit76that may be used to analyze and allow for manipulation of selected images. The images may be stored with the imaging system24and/or stored in a selected image memory90. Further, various instructions such as tracking, registration, and the like may be stored in the navigation memory74.

With continuing reference toFIG. 1, during a selected procedure, such as a decompression, bone spur removal, tumor removal, or the like, a procedure may occur to remove a selected portion of the subject20. It may be selected, during the procedure, to attempt or ensure minimizing or eliminating contact of a selected instrument, such as the navigated instrument16, relative to selected areas of the subject20. In various embodiments, a decompression or tumor removal may occur relative to one or more of the vertebrae20v1or20v2. It is understood, however, that the vertebrae20vare generally near nerve tissues and nerve bundles, such as the spinal cord and nerve roots or bundles that extend from the spinal cord to various portions of the subject20. It may be selected, such as by the user12, to attempt to eliminate contact or movement of the instrument into the nerve tissues.

For example, with additional reference toFIG. 2, the vertebra20v1may be included in the image30as imaged vertebra20vi. The vertebra20vmay include various anatomical features such as a vertebral body100, a first pedicle104, a second pedicle105, a spinous process108, a facet joint, the lamina, and transverse processes112. The vertebra20vi, including the various anatomical portions, as discussed above, may surround or define a vertebral foramen116. Within the vertebral foramen116the spinal cord (not specifically illustrated) may be positioned. The spinal cord may extend from near the head20hof the subject20through the vertebral foramen116of all of the vertebrae to various portions of the anatomy. Nerve bundles or roots may extend from the spinal cord near the pedicles104,105. Accordingly, impingement or boney growths near the pedicles104,105and/or the body100may extend into the nerve bundle or root regions120. Removal of the bony growths, such as bone spurs or tumors, may be selected to relief pressure on the nerve bundles.

During a selected procedure, the user12and/or the surgical robot may move the instrument16to perform the bone removal procedure. In various embodiments, the instrument16may include a working end130(FIG. 1). The working end130may include any appropriate working end such as a burr, grater, cutter, or the like. The working end130may be positioned relative to selected portions of the anatomy, such as a bone spur or tumor, to remove the selected portion of the anatomy. In the decompression procedure, therefore, pressure may be removed from the nerve bundle, including the spinal cord, to increase a volume or are of the spinal canal116or the area near the pedicle104where the nerve bundles exit.

The instrument16may be tracked with the tracking device56with an appropriate tracking system, including the optical localizer82and/or the EM localizer40. A known geometry of the instrument16allows the determination of the position of the working end130relative to the tracking device56even when the tracking device is not fixed at the distal end130, as is understood in the art as discussed above. It is understood, however, that any appropriate navigation system be used to track the location of the instrument16with the tracking device56. In various embodiments, the tracking device56may include one or more elements (e.g. spheres) that are viewable by the cameras of the optical localizer82. Therefore the user12may move the instrument16, including the working end130, while it is tracked with the navigation system10. As discussed above the patient20may be registered to the images30such that a position of the tracked instrument16may be illustrated relative to the images30, such as with the icon16i. Further, specific portions of the instrument may also be tracked, such as the working end130, and may also be illustrated with appropriate icons such as a working end icon130i.

The user12may also specifically define selected areas relative to the anatomy, such as the vertebrae20v1and20v2and the nerve bundles in the spinal canal116. The predefined areas may be defined relative to the vertebrae20vusing the images30or other appropriate defining or identifying regions or methods.

With continuing reference toFIG. 1andFIG. 2, the user12may view the image30at any appropriate time, such as immediately prior to a surgical procedure, or other appropriate procedure, during a planning phase. The planning phase may be any time prior to placing the instrument within the subject20, such as hours or days before a procedure, or at any appropriate time. Nevertheless, during the planning phase, the user12may define working areas or planned working areas and nonworking or non-planned working areas. In defining the areas, the user12may view the images30or any appropriate portion to define the selected areas. For example, as illustrated inFIG. 2, the user may define an area within the vertebral foramen116as a no-go or a no-planned go area140. The user12may also define areas near the pedicles104,105as planned go areas142. As understood by one skilled in the art, however, the pedicles104,105may be near where nerve bundles exit the vertebral foramen116through an opening near or adjacent to the pedicles104,105. Accordingly the user12may define a second or additional no-go or no-planned go area146. The user12may further define other areas within the image30as go or no-go areas. Each of the areas or volumes140,142,146may be defined with a discrete edge or boundary.

The user may define the areas using selected inputs72, including a keyboard, mouse, or finger or the like. Additionally, computer algorithms may define the selected area. For example, the display device32may accept touch input such as with a capacitive display and/or selected input pen. The user12may trace areas or volumes and define the areas or volumes as go or no-go areas for a selected procedure. As the images30are registered to the patient or subject20during a selected procedure, the defined areas140,142,146, may then be determined in the subject space of the subject20. When tracking the instrument16, the navigation system10may then determine whether the instrument16, or at least a portion thereof such as the working end130, is in one of the predetermined areas or volumes140,142,146. Accordingly, the navigation processing unit70may access the images, which may be stored, compare them to a tracked location of the instrument16, including the working end130, as discussed further herein.

The user12may also define a selected distance from the defined boundary or volumes140,142,146. For example, an approach area or distance may include increments of 0.1 mm to about 1 mm. For example the boundary140of the vertebral foramen116may be defined by the user12. Also defined by the user, and/or defined by the navigation system10, may be an approach distance or boundary relative to the defined area140. The approach distance may be used to determine a notice or indication to the user12as the instrument16moves toward the defined area140, but yet has not engaged or impinged upon the area140. Accordingly, the gradation or incremental distance measurements may be any appropriate increment such as 0.1 mm, 0.2 mm, 0.5 mm, or the like. Further a maximum distance from the area140may be defined as a no-notice or safe area separate from the planned go area142. For example, a maximum distance of 0.5 cm to about 1.5 cm may be determined by the user12and/or predetermined by the navigation system10. Thus, as discussed further herein, when the instrument16is tracked and the position of the instrument16is determined to be outside of the minimum distance (e.g. at least 1 cm) away from the area140, including a boundary defining the area140, no indication may be provided to the user of a proximity or close proximity of the instrument16to the no-go area140. Once the instrument passes the minimum distance or fence, however, the user12may be given an indication of proximity of the instrument16to the predetermined area.

With continuing reference toFIGS. 1 and 2, the user12may perform a procedure after determining the selected areas or volumes, such as the no-go areas or volumes140,146and the planned go area or volume142. Each of the volumes140,142,146may include boundaries or borders defined by the user12or computer algorithm. The user12and/or surgical robot may then use the tracked instrument16, including the working end130, to move the working end130toward the planned go area142. As the instrument16moves toward the area of the subject20, such as near the vertebrae20v, indications may be made on the display device32.

Indications may include various indications on one of more views. Generally, the indications may include visually perceptible indications displayed with the display device32. The indications may be displayed relative to and/or directly on the image30. The indications provide a visual indication to the user12of the relative tracked position of the instrument16and/or the working end130. The indications may be visual representations of color, size, opacity, gradient, etc.

For example, as illustrated inFIG. 2, the display device32may include the images30in a plurality of windowed views. For example, an axial view200may be displayed of the image30, a sagittal view210of the image30may be displayed, and a 3D model in a window216may be displayed of the image30. Each of the displays200,210,216may display a selected view of the image30for reference by the user12. Each of the views may include indications relative thereto. As discussed herein, the indication may be directly on the image and/or placed a distance from the image30. The indication is regarding the tracked position of the instrument16relative to one or more of the predefined areas140-146.

Indications may include an indication bar or portion220,222, or224in the respective view windows200,210,216. The bars may be positioned in the respective windows in any appropriate manner, such as to grow horizontally and/or change in a visual manner (e.g. color, opacity, gradient, etc.) relative to the display windows. As discussed further herein, therefore, the indications220,222,224may increase in size, change color, and the like depending upon the tracked position of the instrument16. Further, a separate window228may be positioned on the display device32relative to one or more of the other windows to provide an overall indication232and may include a label such as proximity alert or proximity indication234. The indicator232of the proximity indication window228may include a maximum or closest indication of any of the indicators to one or more of the no-go areas140,146. Accordingly, each of the individual windows including the indicators220,222,224, may include indication regarding a position of the instrument16relative to the defined areas in each of the respective views while the proximity indication232may provide an overall closest indication which may vary amongst the different views given the three-dimensional nature of the vertebrae20vand the subject20. Additionally, audible indications may be used relative to the pre-defined boundaries or borders.

With continuing reference toFIG. 2, the indications may further include indications at or directly on the image30. For example, as illustrated inFIG. 2, near the pedicles104,105and near the spinous process108around the areas defined by the user140,142,146, the image30may appear to be color coded or otherwise visually distinguishable from surrounding areas. For example, the indicators220may be augmented or alternatively provided as color coding portions of the image30. Accordingly, the image30may include an indication coloring or marking240near the pedicle140, a coloring or indication242near or at the pedicle105, and a coloring or indication244near or at the spinous process108. Each of the direct indications240,242,244, may change (e.g. change color, change darkness, change visual indication, change audible alert, etc.) based upon a tracked position of the instrument16relative to the defined areas140,142,146. For example, similar to the indications220,222,224,232, the direct image indications240,242,244may darken or change color from a first color, such as yellow, to a darker or second color, such as red, as the instrument moves toward the no-go area146in the respective views. When audible indications are given, the type, frequency, volume, etc. of audible indication may also change rather than and/or in addition to a color change.

The robot25may also be provided to give the indication, rather than the visual indicator, noted above, the indication may be feedback (e.g. haptic feedback or force feedback) to the user12and or limit placement or movement with the robot25itself. The robot25, for example, may be moved by the user12with the instrument within a manipulator and/or guide portion of the robot25. The robot25may, therefore, may be used to provide the indication to the user such as with haptic feedback to the user12as the robot25is moved to move the instrument16relative to the define areas or volumes, as discussed above. The type or intensity of the haptic feedback may change. Further, the robot25may be configured and operated to limit movement (e.g. stop movement) of the instrument16relative to the defined areas or volumes140,142,146.

As illustrated inFIG. 2, however, when the instrument16is near only a selected portion, such as the pedicle105, only that portion of the indication242may alter or change appearance due to the tracked position of the instrument16. Accordingly, the indications240,244, may remain substantially unchanged and only identify those regions that are generally being monitored for the possible location of the instrument16, including the working end130, relative to the image30. It is further understood that the user12and/or the navigation system10automatically determines a selected portion of the instrument16to be tracked or identified with the indications. For example, the user12may identify the working end130as the relevant portion of the instrument16to be indicated with the indicators while a shaft connected to the working end130may be less critical or identified as not being relevant to the indications for providing to the user.

As discussed further herein, the various indications may be altered in visual appearance, such as color or color density, to provide indication to the user12of a tracked position of the working end130relative to selected pre-defined areas or volumes, such as the no-go volume146. As discussed above, as the working end130moves toward or past a boundary, such as 1 cm away from the defined no-go volume146, the indicators may appear and begin to change as the working end130continues to move closer to the no-go area. As illustrated inFIG. 2, in most orientations the working end130of the instrument16is not substantially near or within the boundary and accordingly in most of the views the indication is low or not presented.

Turning reference toFIG. 3, however, as the instrument16is moved by the user12and/or surgical robot the respective or various indications may also alter or change appearance to provide feedback and indication to the user12of a tracked position of the working end130relative to the no-go146or140. As illustrated inFIG. 3in the axial view, the working end icon130iis near the vertebral foramen116and the predetermined no-go volume140. Accordingly the indication220is increased in dimension relative to the image30and may also include an altered color or visual indication. In various examples, an initial portion of the indicator220may include a light or yellow color220i. As the indicator220grows the indicator may increase in dimension and change color, such as including a gradient from yellow to red (including orange) and a red portion220r.

The indicator220, therefore, may provide a plurality of visual indications or audible indications to the user12that the working end130is near the predetermined no-go region140. The overall proximity indicator232may also similarly change in color and dimension given the change of the indicator220. In the sagittal view and the respective orientation presented thereby, however, the indicator222may not change given the relative location of the working end130. Accordingly, in various views the working end icon130imay at different positions relative to the predefined go or no-go areas and the respective indicators may also be different. Accordingly the 3D view216may also indicate or have the indicator224change to include the change in color, size, and/or opacity for viewing by the user12. It is understood, however, that the user12may also have an assistant that is able to provide an indication, such as an auditory indication, that the visual indicators have changed. In addition the navigation system may provide additional indications to the user12, such as auditory indications and haptic indications (e.g. haptic feedback through the instrument16) and/or the surgical robot to the user12.

Turning reference toFIG. 4, as the instrument16is moved the various indicators may change. For example, the indicator220may return or reduce in size and change color when the working end130, represented by the icon130i, is moved away from a selected no-go area, such as the vertebral foramen116volume140. Similarly the direct image indications240,244,242, may also be light (e.g. yellow) in color or indication, and/or revert to the initial non-proximity indication. However, in the sagittal view window210, the indicator222may have changed to include a different size, color, or the like, as discussed above. Similarly the overall proximity indication232may change given the indicator222. The three-dimensional view indicator224may also indicate the proximity of the working end130relative to the selected predefined areas or volumes. Accordingly, as the user12and/or surgical robot moves the instrument16that is tracked with the navigation system10, the indicators on the display device32may change relative to the different views or view windows displayed thereon. Accordingly, the user12may be continuously updated, such as in substantially real time, regarding the tracked position of the instrument12and proximity relative to the different predefined areas.

With reference toFIG. 5, the instrument may be further moved, such as nearing an end of the procedure, such as a decompression procedure. When a procedure is nearly complete, the instrument16may be moved away from the vertebrae20v. As the instrument is moved away, the various indicators220,222,224,232, in the various windows may all reduce in size and/or change color to a preliminary or initial color. Similarly the direct image indicators240,242,244, may also all change or revert to an initial color, opacity, etc. It is understood that the direct image indicators240,242,244, may also be provided in any appropriate view200,210,216.

Accordingly, as the user12performs the procedure on the subject20, for performing any appropriate procedure, such as bone removal, disc removal, soft tissue resection, etc. the various indicators, including the indicators in the selected windows and/or the direct image indicators, may alter or change to provide a visual or audible indication to the user12of the tracked position of the instrument relative to the predefined areas or volumes and/or the predefined distances relative to edges or boundaries thereof. Accordingly, the user12may view both the icons16iand130irepresenting the tracked position of the instrument16and working end130, respectively, along with the additional visual indicators of the absolute tracked position of the working end130relative to selected predefined areas. The instrument16may be used to move and/or remove any selected material in a subject. The indicators may be fixed relative to the image, but may change in color, opacity, size, etc. to provide the indication to the user12. The user12may, therefore, be provided substantially immediate feedback regarding the tracked position of the working end130of the instrument16relative to predefined areas or volumes of the subject20. Thus, the procedure may be performed substantially efficiently as the user12is provided an indication in addition to the icon representing the instrument16and working in130on the display device32.