System and method for navigated drill guide

A system for tracking a navigated instrument. The system can include a first elongated instrument and a second elongated instrument. The first elongated instrument can have a first proximal end and a first distal end. The first elongated instrument can be adapted to be positioned relative to an anatomy. The second elongated instrument can move adjacent to the first elongated instrument. The second elongated instrument can have a second proximal end and a second distal end. The system can also include at least one tracking device coupled to the second elongated instrument. When the second elongated instrument is in a first position, the at least one tracking device tracks the first distal end of the first elongated instrument, and when the second elongated instrument is in a second position, the at least one tracking device tracks the second distal end of the second elongated instrument.

FIELD

The present disclosure relates generally to navigated surgery, and more specifically, to systems and methods for a navigated drill guide.

BACKGROUND

Image guided medical and surgical procedures utilize patient images obtained prior to or during a medical procedure to guide a physician performing the procedure. Recent advances in imaging technology, especially in imaging technologies that produce highly-detailed, two, three, and four dimensional images, such as computed tomography (CT), magnetic resonance imaging (MRI), fluoroscopic imaging (such as with a C-arm device), positron emission tomography (PET), and ultrasound imaging (US) has increased the interest in navigated medical procedures.

Generally, during a navigated procedure, images are acquired by a suitable imaging device for later display on a workstation. The navigation system tracks the patient, instruments and other devices in the surgical field or patient space. These tracked devices are then displayed relative to the image data on the workstation in image space. In order to track the patient, instruments and other devices, the patient, instruments and other devices can be equipped with tracking devices.

Generally, tracking devices are coupled to an exterior surface of the instrument, and can provide the surgeon, via the tracking system, an accurate depiction of the location of that instrument in the patient space. In cases where a first instrument moves within a second instrument, however, it can be difficult to accurately determine the location of the distal most end of the instrument assembly, as depending upon the movement of the first instrument within the second instrument, either the first instrument or the second instrument can form the distal most end. For example, in the case of a drill bit that moves within a drill guide, depending upon the advancement of the drill bit, the end of the drill guide or the end of the drill bit can form the distal most end of the instrument assembly.

SUMMARY

A system for tracking a navigated instrument. The system can include a first elongated instrument and a second elongated instrument. The first elongated instrument can have a first proximal end and a first distal end. The first elongated instrument can be adapted to be positioned relative to an anatomy. The second elongated instrument can move adjacent to the first elongated instrument. The second elongated instrument can have a second proximal end and a second distal end. The system can also include at least one tracking device coupled to the second elongated instrument. When the second elongated instrument is in a first position, the at least one tracking device tracks the first distal end of the first elongated instrument, and when the second elongated instrument is in a second position, the at least one tracking device tracks the second distal end of the second elongated instrument.

Provided is a system for tracking a navigated instrument. The system can include a guide instrument. The guide instrument can have a first proximal end and a first distal end. The guide instrument can define a first bore that can be adapted to slideably receive an elongated instrument that has a second distal end. The guide instrument can be positionable adjacent to an anatomy. The system can also include at least one electromagnetic tracking device coupled to the elongated instrument. The at least one electromagnetic tracking device can be moveable relative to the guide instrument. When the elongated instrument is in a first position, the at least one electromagnetic tracking device tracks the first distal end of the guide instrument, and when the elongated instrument is in a second position, the at least one electromagnetic tracking device tracks the second distal end of the elongated instrument.

A method for tracking a navigated instrument. The method can include positioning a first elongated instrument relative to a second elongated instrument having a first proximal end and a first distal end, the second elongated instrument having a second proximal end and a second distal end. The method can also include positioning at least one tracking device on the second elongated instrument. The method can include moving the second elongated instrument that adjacent to the first elongated instrument. The method can further include tracking the at least one tracking device, and determining, based on the tracking of the at least one tracking device, a location of the first distal end of the first elongated instrument or the second distal end of the second elongated instrument.

Provided is a system for tracking a navigated instrument. The system can include a guide instrument. The guide instrument can have a first proximal end, a first distal end and can define a first bore that can be adapted to slideably receive an elongated instrument that has a second distal end. The guide instrument can be positionable adjacent to an anatomy. The system can also include at least one tracking device coupled about the elongated instrument. The at least one tracking device can be moveable relative to the guide instrument. When the elongated instrument is in a first position, the at least one tracking device can track the first distal end of the guide instrument, and when the elongated instrument is in a second position, the at least one tracking device can track the second distal end of the elongated instrument. The relative movement of the elongated instrument within the guide instrument can act to vary a signal induced in the at least one tracking device.

A method for tracking a navigated instrument is also provided. The method can include positioning a first elongated instrument relative to a second elongated instrument. The first elongated instrument can include a first proximal end and a first distal end, and the second elongated instrument can have a second proximal end and a second distal end. The method can further include positioning at least one tracking device on the second elongated instrument, and moving the second elongated instrument adjacent to the first elongated instrument to vary a signal induced in the at least one tracking device. The method can further include tracking the at least one tracking device, and determining, based on the tracking of the at least one tracking device, a location of the first distal end of the first elongated instrument or the second distal end of the second elongated instrument.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. As indicated above, the present teachings are directed towards providing a system and method for a navigated guide for use with a surgical procedure. It should be noted, however, that the present teachings could be applicable to any appropriate procedure in which it is desirable to determine a position and trajectory of an object that is hidden from view, such as a deep brain stimulator (DBS) probe. Further, as used herein, the term module refers to an application specific integrated circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that executes one or more software or firmware programs, a combinational logic circuit, and/or other suitable software, firmware programs or components that provide the described functionality. Therefore, it will be understood that the following discussions are not intended to limit the scope of the appended claims.

FIG. 1is a diagram illustrating an overview of a navigation system10that can be used for various procedures. The navigation system10can be used to track the location of an implant, such as a spinal implant or orthopedic implant, relative to a patient12. Also the navigation system10can track the position and orientation of various instruments. It should further be noted that the navigation system10may be used to navigate any type of instrument, implant, or delivery system, including: guide wires, arthroscopic systems, orthopedic implants, spinal implants, deep-brain stimulator (DBS) probes, etc. Moreover, these instruments may be used to navigate or map any region of the body. The navigation system10and the various instruments may be used in any appropriate procedure, such as one that is generally minimally invasive, arthroscopic, percutaneous, stereotactic, or an open procedure.

The navigation system10may include an imaging device14that is used to acquire pre-, intra-, or post-operative or real-time image data of a patient12. Alternatively, various imageless systems can be used or images from atlas models can be used to produce patient images, such as those disclosed in U.S. Patent Pub. No. 2005-0085714, filed Oct. 16, 2003, entitled “METHOD AND APPARATUS FOR SURGICAL NAVIGATION OF A MULTIPLE PIECE CONSTRUCT FOR IMPLANTATION,” incorporated herein by reference. The imaging device14can be, for example, a fluoroscopic x-ray imaging device that may be configured as an O-arm™ or a C-arm16having an x-ray source18, an x-ray receiving section20, an optional calibration and tracking target22and optional radiation sensors24. It will be understood, however, that patient image data can also be acquired using other imaging devices, such as those discussed above and herein.

An imaging device controller28, that can control the C-arm16, can capture the x-ray images received at the x-ray receiving section20and store the images for later use. The controller28may also be separate from the C-arm16and/or control the rotation of the C-arm16. For example, the C-arm16can move in the direction of arrow A or rotate about a longitudinal axis12aof the patient12, allowing anterior or lateral views of the patient12to be imaged. Each of these movements involves rotation about a mechanical axis32of the C-arm16. The movements of the imaging device14, such as the C-arm16can be tracked with a tracking device33.

In the example ofFIG. 1, the longitudinal axis12aof the patient12is substantially in line with the mechanical axis32of the C-arm16. This can enable the C-arm16to be rotated relative to the patient12, allowing images of the patient12to be taken from multiple directions or about multiple planes. An example of a fluoroscopic C-arm X-ray device that may be used as the optional imaging device14is the “Series 9600 Mobile Digital Imaging System,” from GE Healthcare, (formerly OEC Medical Systems, Inc.) of Salt Lake City, Utah. Other exemplary fluoroscopes include bi-plane fluoroscopic systems, ceiling fluoroscopic systems, cath-lab fluoroscopic systems, fixed C-arm fluoroscopic systems, isocentric C-arm fluoroscopic systems, 3D fluoroscopic systems, etc. An exemplary O-arm™ imaging device is available from Medtronic Navigation Littleton of Littleton, Mass.

In operation, the imaging device14generates x-rays from the x-ray source18that propagate through the patient12and calibration and/or tracking target22, into the x-ray receiving section20. This allows direct visualization of the patient12and radio-opaque instruments in the cone of X-rays. It will be understood that the tracking target22need not include a calibration portion. The x-ray receiving section20generates image data representing the intensities of the received x-rays. Typically, the x-ray receiving section20includes an image intensifier that first converts the x-rays to visible light and a charge coupled device (CCD) video camera that converts the visible light into digital image data. X-ray receiving section20can also be a digital device that converts x-rays directly to digital image data for forming images, thus potentially avoiding distortion introduced by first converting to visible light. With this type of digital C-arm, which is generally a flat panel device, the optional calibration and/or tracking target22and the calibration process discussed below may be eliminated. Also, the calibration process may be eliminated or not used at all for various procedures. Alternatively, the imaging device14may only take a single image with the calibration and tracking target22in place. Thereafter, the calibration and tracking target22may be removed from the line-of-sight of the imaging device14.

Two dimensional fluoroscopic images that may be taken by the imaging device14are captured and stored in the controller28. Multiple two-dimensional images taken by the imaging device14may also be captured and assembled to provide a larger view or image of a whole region of a patient, as opposed to being directed to only a portion of a region of the patient12. For example, multiple image data of a patient's leg may be appended together to provide a full view or complete set of image data of the leg that can be later used to follow contrast agent, such as Bolus tracking.

Patient image data100can be forwarded from the controller28to a navigation computer and/or processor or workstation34. It will also be understood that the image data is not necessarily first retained in the controller28, but may also be directly transmitted to the workstation34. The workstation34can include a display36, a user input device38and a control module101. The workstation34can also include or be connected to an image processor, navigation processor, and memory to hold instruction and data. The workstation34can provide facilities for displaying the patient image data100as an image on the display36, saving, digitally manipulating, or printing a hard copy image of the received patient image data100.

The user input device38can comprise any device, such as an user input device38, that can enable a user to interface with the workstation34, such as a touchpad, touch pen, touch screen, keyboard, mouse, wireless mouse, or a combination thereof. The user input device38allows a physician or user39to provide inputs to control the imaging device14, via the C-arm controller28, or adjust the display settings of the display36.

The control module101can determine the location of the tracking device58with respect to the patient space, and can output image data102to the display36. The image data102can comprise an icon103that provides an indication of the location of a tracking device with respect to the patient space, illustrated on the patient image data100, as will be discussed herein. It should be noted that the patient image data100can comprise at least one of data from the navigation system10, image data acquired by the imaging device14, patient information entered by the user through the user input device38, pre-operative images, or combinations thereof.

When the x-ray source18generates the x-rays that propagate to the x-ray receiving section20, the radiation sensors24can sense the presence of radiation, which is forwarded to the controller28, to identify whether or not the imaging device14is actively imaging. This information is also transmitted to a coil array controller48, further discussed herein.

While the imaging device14is shown inFIG. 1, any other alternative 2D, 3D or 4D imaging modality may also be used. For example, any 2D, 3D or 4D imaging device, such as an O-arm™ imaging device, isocentric fluoroscopy, bi-plane fluoroscopy, ultrasound, computed tomography (CT), multi-slice computed tomography (MSCT), magnetic resonance imaging (MRI), high frequency ultrasound (HFU), positron emission tomography (PET), optical coherence tomography (OCT), intra-vascular ultrasound (IVUS), ultrasound, intra-operative CT or MRI may also be used to acquire 2D, 3D or 4D pre- or post-operative and/or real-time images or patient image data100of the patient12. For example, an intra-operative MRI system, such as the PoleStar® MRI system sold by Medtronic, Inc. The images of the patient12may also be obtained and displayed in two, three or four dimensions. In more advanced forms, four-dimensional surface rendering regions of the body may also be achieved by incorporating patient data or other data from an atlas or anatomical model map or from pre-operative image data captured by MRI, CT, or echocardiography modalities. A more detailed discussion on optical coherence tomography (OCT), is set forth in U.S. Pat. No. 5,740,808, issued Apr. 21, 1998, entitled “Systems And Methods For Guiding Diagnostic Or Therapeutic Devices In Interior Tissue Regions” which is hereby incorporated by reference.

Image datasets from hybrid modalities, such as positron emission tomography (PET) combined with CT, or single photon emission computer tomography (SPECT) combined with CT, could also provide functional image data superimposed onto anatomical data to be used to confidently reach target sites within the patient12. It should further be noted that the imaging device14, as shown inFIG. 1, provides a virtual bi-plane image using a single-head C-arm fluoroscope as the imaging device14by simply rotating the C-arm16about at least two planes, which could be orthogonal planes, to generate two-dimensional images that can be converted to three-dimensional volumetric images. By acquiring images in more than one plane, the icon103representing the location of an impacter, stylet, reamer driver, taps, drill, deep-brain stimulator (DBS) probes, or other instrument, introduced and advanced in the patient12, may be superimposed in more than one view and included in the image data102displayed on the display36.

With continuing reference toFIG. 1, the navigation system10can further include an electromagnetic navigation or tracking system44that includes a localizer, such as a coil array46and/or second coil array47, the coil array controller48, a navigation probe interface50, a device or instrument52(e.g. catheter, needle, DBS probe, etc., as discussed herein), a dynamic reference frame (DRF)54and one or more tracking devices58. Other tracking systems can include an optical tracking system44b, for example the StealthStation® Treon® and the StealthStation® Tria® both sold by Medtronic Navigation, Inc. Further, other tracking systems include acoustic, radiation, radar, infrared, etc., or a hybrid system, such as a system that includes components of both an electromagnetic and optical tracking system, etc. The instrument52and the DRF54can each include the tracking device(s)58.

The tracking device58or any appropriate tracking device as discussed herein, can include both a sensor, a transmitter, or combinations thereof and can be indicated by the reference numeral58. Further, the tracking devices58can be wired or wireless to provide a signal or emitter or receive a signal from a system. Nevertheless, a tracking device58acan include an electromagnetic coil to sense a field produced by the localizing coil array46or47, while a tracking device58bcan include reflectors that can reflect a signal to be received by the optical localizer or tracking system44b. Nevertheless, one will understand that the tracking device(s)58can receive a signal, transmit a signal, or combinations thereof to provide information to the navigation system10to determine a location of the tracking device58. In addition, it will be understood that the tracking device33of the C-arm16could comprise a suitable tracking device58. The navigation system10can then determine a position of the instrument52based on the location of the tracking device58to allow for navigation relative to the patient12and the patient space.

With regard to the optical localizer or tracking system44b, the optical tracking system44bcan transmit and receive an optical signal, or combinations thereof. An optical tracking device58bcan be interconnected with the instrument52, or other devices such as the DRF54. As generally known, the optical tracking device58bcan reflect, transmit or receive an optical signal to/from the optical localizer or tracking system44bthat can be used in the navigation system10to navigate or track various elements. Therefore, one skilled in the art will understand, that the tracking devices58can be any appropriate tracking device to work with any one or multiple tracking systems.

An electromagnetic tracking system44can include the coil arrays46,47but the coil arrays46,47may also be supplemented or replaced with a mobile localizer (not shown). The mobile localizer may be one such as that described in U.S. patent application Ser. No. 10/941,782, filed Sep. 15, 2004, and entitled “METHOD AND APPARATUS FOR SURGICAL NAVIGATION”, herein incorporated by reference. As is understood, the coil array46,47can transmit signals that are received by the tracking device(s)58. The tracking device(s)58can then transmit or receive signals based upon the transmitted or received signals from or to the coil arrays46,47.

Further included in the navigation system10may be an isolator circuit or assembly (not specifically shown). The isolator circuit or assembly may be included in a transmission line to interrupt a line carrying a signal or a voltage to the navigation probe interface50. Alternatively, the isolator circuit included in the isolator box may be included in the navigation probe interface50, the instrument52, the DRF54, the transmission lines coupling the instruments52, or any other appropriate location. The isolator assembly is operable to isolate any of the instruments or patient coincidence instruments or portions that are in contact with the patient12should an undesirable electrical surge or voltage take place.

In addition, the navigation system10can further include a gating device or an ECG or electrocardiogram (not shown), which is attached to the patient12, via skin electrodes, and in communication with the coil array controller48. Respiration and cardiac motion can cause movement of cardiac structures relative to the instrument52, even when the instrument52has not been moved. Therefore, images can be acquired from the imaging device14based on a time-gated basis triggered by a physiological signal. For example, the ECG or EGM signal may be acquired from the skin electrodes or from a sensing electrode included on the instrument52or from a separate reference probe (not shown). A characteristic of this signal, such as an R-wave peak or P-wave peak associated with ventricular or atrial depolarization, respectively, may be used as a triggering event for the coil array controller48to drive the coils in the coil arrays46,47. This triggering event may also be used to gate or trigger image acquisition during the imaging phase with the imaging device14. By time-gating the image data102and/or the navigation data, the icon103of the location of the instrument52in image space relative to the patient space at the same point in the cardiac cycle may be displayed on the display36. Further detail regarding the time-gating of the image data and/or navigation data can be found in U.S. Pub. Application No. 2004-0097806, entitled “Navigation System for Cardiac Therapies,” filed Nov. 19, 2002, which is hereby incorporated by reference.

It should further be noted that the entire electromagnetic tracking system44or parts of the electromagnetic tracking system44may be incorporated into the imaging device14, including the radiation sensors24, the workstation34and the control module101. Incorporating the electromagnetic tracking system44can provide an integrated imaging and tracking system. Any combination of these components can also be incorporated into the imaging device14, which again can include a fluoroscopic C-arm imaging device or any other appropriate imaging device.

The coil arrays46,47are shown attached to the operating table49. It should be noted, however, that the coil arrays46,47can also be positioned at any other location as well and can also be positioned in the items being navigated. The coil arrays46,47include a plurality of coils that are each operable to generate distinct electromagnetic fields into the navigation region of the patient12, which is sometimes referred to as patient space. Representative electromagnetic systems are set forth in U.S. Pat. No. 5,913,820, entitled “Position Location System,” issued Jun. 22, 1999 and U.S. Pat. No. 5,592,939, entitled “Method and System for Navigating a Catheter Probe,” issued Jan. 14, 1997, each of which are hereby incorporated by reference.

The coil arrays46,47can be controlled or driven by the coil array controller48. The coil array controller48can drive each coil in the coil arrays46,47in a time division multiplex or a frequency division multiplex manner. In this regard, each coil can be driven separately at a distinct time or all of the coils can be driven simultaneously with each being driven by a different frequency. Upon driving the coils in the coil arrays46,47with the coil array controller48, electromagnetic fields are generated within the patient12in the area where the medical procedure is being performed, which is again sometimes referred to as patient space. The electromagnetic fields generated in the patient space induce currents in a tracking device(s)58positioned on or in the instrument52. These induced signals from the instrument52are delivered to the navigation probe interface50and can be subsequently forwarded to the coil array controller48.

The navigation probe interface50may provide all the necessary electrical isolation for the navigation system10. The navigation probe interface50can also include amplifiers, filters and buffers to directly interface with the tracking device58in the instrument52. Alternatively, the tracking device58, or any other appropriate portion, may employ a wireless communications channel, such as that disclosed in U.S. Pat. No. 6,474,341, entitled “Surgical Communication Power System,” issued Nov. 5, 2002, herein incorporated by reference, as opposed to being coupled directly to the navigation probe interface50.

Various portions of the navigation system10, such as the instrument52, the DRF54and others as will be described in detail below, are equipped with at least one, and generally multiple, tracking devices58, that may also be referred to as localization sensors. The tracking device58can be a handle or inserter that interconnects with an attachment and may assist in placing an implant. The instrument52can include a graspable or manipulable portion at a proximal end and the tracking device58may be fixed near the manipulable portion of the instrument52. The instrument52may be any appropriate instrument, such as an instrument for preparing a portion of the patient12or an instrument for positioning an implant.

In an alternate embodiment, the electromagnetic sources or generators may be located within the instrument52, DRF54, and one or more receiver coils may be provided externally to the patient12forming a receiver coil array similar to the coil arrays46,47. An additional representative alternative localization and tracking system is set forth in U.S. Pat. No. 5,983,126, entitled “Catheter Location System and Method,” issued Nov. 9, 1999, which is hereby incorporated by reference. Alternatively, the localization system may be a hybrid system that includes components from various systems.

The DRF54of the tracking system44can also be coupled to the navigation probe interface50to forward the information to the coil array controller48. The DRF54, according to various embodiments, can include a small magnetic field detector. The DRF54may be fixed to the patient12adjacent to the region being navigated so that any movement of the patient12is detected as relative motion between the coil arrays46,47and the DRF54. This relative motion can be forwarded to the coil array controller48, which can update the registration correlation and maintain accurate navigation, as further discussed herein. The DRF54may include any appropriate tracking device(s)58used by the navigation system10. Therefore, the DRF54can include an optical tracking device, as indicated by reference number58b, or acoustic, etc. If the DRF54is used with an electromagnetic tracking device58ait can be configured as a pair of orthogonally oriented coils, each having the same center or may be configured in any other non-coaxial or co-axial coil configurations (not specifically shown).

Briefly, the navigation system10operates as follows. The navigation system10creates a translation map between all points in the radiological image generated from the imaging device14and the corresponding points in the patient's anatomy in patient space. After this map is established, whenever a tracked instrument, such as the instrument52is used, the workstation34in combination with the coil array controller48and the controller28uses the translation map to identify the corresponding point on the pre-acquired image or atlas model, which is displayed on display36. This identification is known as navigation or localization. The icon103representing the localized point or instruments52can be shown as image data102on the display36, as will be discussed herein.

To enable navigation, the navigation system10must be able to detect both the position of the patient's anatomy and the position of the instrument52or attachment member (e.g., tracking device58) attached to the instrument52. Knowing the location of these two items allows the navigation system10to compute and display the position of the instrument52in relation to the patient12on the display36. The tracking system44can be employed to track the instrument52and the anatomy simultaneously.

The tracking system44, if using an electromagnetic tracking assembly, essentially works by positioning the coil arrays46,47adjacent to the patient space to generate a low-energy magnetic field generally referred to as a navigation field. Because every point in the navigation field or patient space is associated with a unique field strength, the tracking system44can determine the position of the instrument52by measuring the field strength at the tracking device58location. The DRF54is fixed to the patient12to identify the location of the patient12in the navigation field. The tracking system44continuously recomputes the relative position of the DRF54and the instrument52during localization and relates this spatial information to patient registration data to enable image guidance of the instrument52within and/or relative to the patient12.

Patient registration is the process of determining how to correlate the position of the instrument52relative to the patient12to the position on the diagnostic or pre-acquired images. To register the patient12, a physician or user39may use point registration by selecting and storing particular points from the pre-acquired images and then touching the corresponding points on the patient's anatomy with a pointer probe (not shown). The navigation system10analyzes the relationship between the two sets of points that are selected and computes a match, which correlates every point in the image data102with its corresponding point on the patient's anatomy or the patient space, as discussed herein. The points that are selected to perform registration are the fiducial markers60, such as anatomical landmarks. Again, the landmarks or fiducial markers60are identifiable on the images and identifiable and accessible on the patient12. The fiducial markers60can be artificial markers that are positioned on the patient12or anatomical landmarks that can be easily identified in the image data102. The artificial landmarks, such as the fiducial markers60, can also form part of the DRF54, such as those disclosed in U.S. Pat. No. 6,381,485, entitled “Registration of Human Anatomy Integrated for Electromagnetic Localization,” issued Apr. 30, 2002, herein incorporated by reference.

The navigation system10may also perform registration using anatomic surface information or path information as is known in the art. The navigation system10may also perform 2D to 3D registration by utilizing the acquired 2D images to register 3D volume images by use of contour algorithms, point algorithms or density comparison algorithms, as is known in the art. An exemplary 2D to 3D registration procedure, is set forth in U.S. Ser. No. 60/465,615, entitled “Method and Apparatus for Performing 2D to 3D Registration” filed on Apr. 25, 2003, hereby incorporated by reference.

Also as discussed herein, a substantially fiducial-less registration system can be provided, particularly if the imaging device14and the tracking system44are substantially integrated. Therefore, the tracking system44would generally know the position of the imaging device14relative to the patient12and fiducial markers60may not be required for registration. Nevertheless, it will be understood that any appropriate type of registration system can be provided for the navigation system10.

In order to maintain registration accuracy, the navigation system10continuously tracks the position of the patient12during registration and navigation. This is because the patient12, DRF54, and coil arrays46,47may all move during the procedure, even when this movement is not desired. Alternatively the patient12may be held immobile once the registration has occurred, such as with a head frame (not shown). Therefore, if the navigation system10did not track the position of the patient12or area of the anatomy, any patient movement after image acquisition would result in inaccurate navigation within that image. The DRF54allows the tracking system44to register and track the anatomy. Because the DRF54is rigidly fixed to the patient12, any movement of the anatomy or the coil arrays46,47is detected as the relative motion between the coil arrays46,47and the DRF54. This relative motion is communicated to the coil array controller48, via the navigation probe interface50, which updates the registration correlation to thereby maintain accurate navigation.

The navigation system10can be used according to any appropriate method or system. For example, pre-acquired images, atlas or 3D models may be registered relative to the patient12and the patient space. Generally, the navigation system10allows the images on the display36to be registered and to accurately display the real time location of the various instruments, such as the instrument52, and other appropriate items, such as DRF54. In addition, the DRF54may be used to ensure that any planned or unplanned movement of the patient12or the coil arrays46,47can be determined and used to correct the image data102on the display36.

Referring now toFIG. 2A, instruments52are shown for use with the optical tracking system44b. In this example, the instruments52can include a drill104and a drill guide106. The drill104can include a sleeve108and a drill bit110. The drill bit110can comprise a conventional drill bit that can engage and remove portions of an anatomy of the patient12, and thus, will not be discussed in great detail herein.

The sleeve108can include an optical tracking device58b, which can be coupled to a body122of the sleeve108. As will be discussed in greater detail below, the body122of the sleeve108can be configured to receive the drill bit110therethrough. With regard to the tracking device58b, the tracking device58bcan be coupled to a proximal end124of the body122of the sleeve108. The tracking device58bcan be responsive to the optical tracking system44b, and thus, can include at least one optical reflector or at least one optical transmitter, or combinations thereof, depending upon the optical tracking system44bemployed with the navigation system10. Further, it should be noted, that although one tracking device58bis illustrated, any number of tracking devices58could be employed, such as an array or a tracking device58b′ illustrated in phantom on the drill guide106, and further, it will be understood that the tracking device58b′ can be arranged with any appropriate number of tracking devices58b, such as three, and further the tracking device58b′ could be arranged in any appropriate pattern or configuration.

With continued reference toFIGS. 1 and 2A, the drill guide106can comprise any suitable guide that enables the user39to direct the motion of the drill bit110, and can include a handle156and a cannula158. As the handle156can comprise any suitable graspable or manipulable portion, the handle156of the drill guide106will not be discussed in greater detail below.

The cannula158can include a proximal end160, a distal end162, and a tube163that can couple the proximal end160to the distal end162. The proximal end160, the distal end162and the tube163can define an opening or throughbore164. The cannula158can also include the optical tracking device58b′, if desired. The tracking device58b′ can be optional, and if employed, can be coupled to the proximal end160of the cannula158. The tracking device58b′ can include one or more optical tracking devices58barranged in a suitable pattern to enable the navigation system10to determine the location of the drill guide106in patient space. The tracking device58b′ can be responsive to the optical tracking system44b, and thus, can include one or more optical reflectors or one or more optical transmitters, or combinations thereof, depending upon the optical tracking system44bemployed with the navigation system10. Further, it should be noted that although four tracking devices58bare illustrated, any number of tracking devices58bcould be employed. In addition, in the case of a hybrid tracking system44, an electromagnetic tracking device58could be employed for use with the drill guide106or sleeve108or vice versa.

In order to assemble the instruments52, the sleeve108can be inserted into the cannula158, and then the drill bit110can be inserted into the sleeve108. Then, the user39(FIG. 1) can use the drill bit110to engage the anatomy. In order to engage the anatomy of the patient12, the user39can move the drill104, and thus, the sleeve108and the drill bit110, within the drill guide106such that as the drill bit110advances into the anatomy, the sleeve108moves relative to the proximal end160of the cannula158. As the sleeve108moves, the tracking system44bcan track the location of the tracking device58b, and thus, can track the location of the distal end of the instrument52. In this regard, as the location of the tracking device58brelative to the sleeve108is known, the tracking system44can track the distal end of either the drill guide106(distal end162) or the drill bit110(tip150). The tracking system44bcan track the distal end162of the cannula158when the tracking device58bremains in its first or initial position, as illustrated inFIG. 2A. As the sleeve108can move into a second position as the drill bit110advances, the movement of the sleeve108can cause the tracking device58bto move a distance Dcthat can correspond to a distance Dtthat the tip150extends beyond the cannula158(as shown in phantom). Thus, based on the displacement of the tracking device58brelative to the cannula158, the navigation system10can determine the distal end162of the cannula158or the tip150of the drill bit110based on the location of the tracking device58b.

In this regard, the single tracking device58bcan provide one degree of freedom information for the navigation system10, while the tracking device58b′ can provide at least three to six degrees of freedom information for the navigation system10. Therefore, if the single tracking device58bis employed with the sleeve108and the tracking device58b′ is employed with the cannula158, then the navigation system10can determine the direction or orientation of the cannula158by tracking the tracking device58b′ and can determine the depth or distance traveled by the sleeve108relative to the cannula158by tracking the tracking device58b. It will be understood, however, that the sleeve108could include at least three tracking devices58b, which would provide the navigation system10with at least three degrees of freedom information for the sleeve108. If the sleeve108has at least three tracking devices58b, then based on the tracking of the tracking devices58bof the sleeve108, the navigation system10could determine the direction or orientation of the sleeve108with or without the tracking device58b′ on the cannula158. It should be understood, however, that any appropriate configuration could be employed to track the movement of the distal end150of the drill bit110relative to the anatomy.

Referring now toFIG. 2B, instruments52are shown for use with the electromagnetic tracking system44. As the instruments52can comprise the same or similar components as the instruments52discussed with regard toFIG. 2A, the same reference numerals will be used herein. In this example, the instruments52can include a drill104aand the drill guide106. The drill104acan include a sleeve108aand the drill bit110. As the drill guide106and drill bit110illustrated inFIG. 2Bcan be substantially similar to the drill guide106and drill bit110illustrated and described with regard toFIG. 2A, the drill guide106and drill bit110will not be discussed in great detail herein with regard toFIG. 2B. Briefly, however, the cannula158of the drill guide106can include an electromagnetic tracking device58a′, if desired. The tracking device58a′ can be optional, and if employed, can be coupled to the proximal end160of the cannula158. The tracking device58a′ will be discussed in greater detail herein with regard to the sleeve108a.

The sleeve108acan include an electromagnetic tracking device58a, which can be coupled to the body122of the sleeve108a. With regard to the tracking device58a, the tracking device58acan be coupled to the proximal end124of the body122of the sleeve108a. The tracking device58a, and the tracking device58a′, can be responsive to the electromagnetic tracking system44, and thus, can include at least one electromagnetic receiver or at least one electromagnetic transmitter, or combinations thereof, depending upon the electromagnetic tracking system44employed with the navigation system10. For example, the tracking device58aand the tracking device58a′ can comprise any suitable electromagnetic transmitters or electromagnetic receivers, and can have any suitable coil configuration, such as a dual coil, tri-axial coil, dual orthogonal coils, dual collinear coils, a delta coil pair or combinations thereof. It should be noted that although the tracking device58aand tracking device58a′ are illustrated in the field of view or exposed, it is not necessary for the tracking device58aand the tracking device58a′ to be within the field of view, and the tracking device58aand the tracking device58a′ can be easily embedded in the instruments52and out of the way of surgeon. In addition, in the case of a hybrid tracking system44, an optical tracking device58bcould be employed for use with the drill guide106or sleeve108aor vice versa.

In order to assemble the instruments52, the sleeve108acan be inserted into the cannula158, and then the drill bit110can be inserted into the sleeve108a. Then, the user39(FIG. 1) can use the drill bit110to engage the anatomy. As discussed, the user39can move the drill104a, and thus, the sleeve108aand the drill bit110, within the drill guide106such that as the drill bit110advances into the anatomy, the sleeve108amoves relative to the proximal end160of the cannula158. As the sleeve108amoves, the electromagnetic tracking system44can track the location of the tracking device58a, and thus, can track the location of the distal end of the instrument52. In this regard, as the location of the tracking device58arelative to the sleeve108ais known, the tracking system44can track the distal end of either the drill guide106(distal end162) or the drill bit110(tip150).

The tracking system44can track the distal end162of the cannula158when the tracking device58aremains in its first or initial position, as illustrated inFIG. 2B. As the sleeve108acan move into a second position as the drill bit110advances, the movement of the sleeve108acan cause the tracking device58ato move a distance Dcthat can correspond to a distance Dtthat the tip150extends beyond the cannula158(as shown in phantom). Thus, based on the displacement of the tracking device58arelative to the cannula158, the navigation system10can determine the distal end162of the cannula158or the tip150of the drill bit110based on the location of the tracking device58a.

In this regard, the single tracking device58acan provide at least three and up to six degrees of freedom information for the navigation system10. Therefore, based on the tracking of the tracking device58aof the sleeve108a, the navigation system10could determine the direction or orientation of the sleeve108awith or without the tracking device58a′ on the cannula158. It should be understood, however, that any appropriate configuration could be employed to track the movement of the distal end150of the drill bit110relative to the anatomy.

With reference now toFIG. 3, exemplary instruments52for use with the electromagnetic tracking system44are shown. As the instruments52can comprise the same or similar components as the instruments52discussed with regard toFIGS. 2A and 2B, the same reference numerals will be used herein. In this example, a first instrument52is a drill104band a second instrument52is a drill guide106b, however, as will be evident from the teachings herein, various other instruments52could employ a tracking device58cas will be discussed herein, such as an instrument52in which it is desirable to measure a position and a trajectory of the instrument52, for example, a DBS probe or a catheter. As the drill104bcan comprise a conventional drill for the anatomy, the drill104bwill not be discussed in great detail herein. Briefly, however, as illustrated inFIG. 3, the drill104bcan comprise a sleeve108band a drill bit110b. The drill104bcan be activated by the user39to advance or retract the sleeve108band the drill bit110binto the anatomy of the patient12.

The sleeve108bcan include a connector116, a spring118, a bushing120and the tracking device58c, each of which can be coupled to the body122of the sleeve108b. With additional reference toFIG. 4, the connector116can be coupled to the proximal end124of the body122of the sleeve108b. The connector116can be generally horseshoe-shaped, and can include a first portion126and a second portion128. The first portion126can be cylindrical to couple the connector116to the sleeve108b. The first portion126can be press-fit to the sleeve108b, or could be bonded or mechanically fastened to the sleeve108b. In addition, as illustrated, the connector116can have a clamshell design such that coupling of the respective second portions128can couple the first portion126to the body122of the sleeve108b.

The second portion128can include a controller130b. The controller130bcan receive the current induced in the tracking device or coil58cthat is coupled to the drill104bwhen the instrument52is placed in the patient space or EM field. The controller130bcan receive the current from the tracking device58c, and can transmit a signal indicative of the current of the tracking device58cto the navigation probe interface50. One or more cables132can be in communication with the tracking device58cand the controller130bto transmit the current from the tracking device58cto the controller130b. At least one cable132acan be in communication with the controller130bto receive the current from the tracking device58c, and can transmit the current to the navigation probe interface50. It will be understood, however, that although a wired connection is illustrated herein, any suitable technique could be used to transmit the current from the tracking device58cto the controller130band the navigation probe interface50, such as a wireless connection.

The spring118can be a helical spring, and can be coiled around the body122of the sleeve108b, near the proximal end124. The spring118can include a first end136and a second end138. The first end136of the spring118can abut the connector116, such that the connector116can retain the spring118on the body122of the sleeve108b. The second end138can include a narrowly coiled section138athat can retain the spring118on the body122of the sleeve108b, but can enable the spring118to be compressed against the drill guide106b.

The bushing120can be coupled to a distal end140of the body112of the sleeve108b. The bushing120can facilitate the easy insertion of the sleeve108binto the drill guide106b. It should be noted, however, that the bushing120can be optional and need not be included in the sleeve108b. The bushing120can form a tip141of the sleeve108b. Spring118can assist in removing the sleeve108from the drill guide106bas will be discussed.

The tracking device58ccan be coupled to the body122of the sleeve108b. The tracking device58ccan comprise one or more electromagnetic sensors or coils142. Generally, the electromagnetic coils142can comprise a tightly coiled conductive wire in which a current can be induced when the electromagnetic field is generated by the coil arrays46,47. The electromagnetic coils142can be in communication with the controller130bof the connector116to transmit the induced current to the controller130b. For example, the electromagnetic coils142could be connected to the controller130via a cable132aas shown inFIG. 3. Alternatively, the electromagnetic coils142could be in wireless communication with the controller130(not shown). Given that each point in the patient space has a unique field strength, the current induced in the electromagnetic coils142can be representative of the physical location of the electromagnetic coils142in the patient space, if the electromagnetic coils142are receiver electromagnetic coils142. Alternatively, if the electromagnetic coils142are transmitter electromagnetic coils142, then the magnetic field generated or produced by the electromagnetic coils142can vary based on the physical location of the electromagnetic coils142in the patient space. The coil array controller48can then determine the physical location of the instrument52based on the known location of the tracking device58cwith respect to the instrument52. The electromagnetic coils142can be positioned adjacent to the distal end140of the sleeve108bto enable the tracking system44to track the distal end140of the drill guide106band the drill bit110bwhen the tracking device58cis positioned within the drill guide106b, as will be discussed.

Generally, two electromagnetic coils142can be positioned adjacent to the distal end140of the instrument52, in this case the sleeve108bof the drill104, to enable the continuous calibration of the instrument52. In this regard, traditionally a calibration detent is used to determine a distance from the tracking device58to the distal end162of the instrument52. In this example, the placement of at least two electromagnetic coils142near the distal end162of the instrument52can enable the tracking system44to continuously monitor the instrument52for changes in a distance D4between the electromagnetic coils142that would indicate that the instrument52has been bent, twisted or deformed. In this regard, the tracking system44can compare the actual distance D4between a first electromagnetic coil142aand a second electromagnetic coil142bbased on the current induced by the coil arrays46,47to a known or predicted distance D4between the first electromagnetic coil142aand the second electromagnetic coil142b. Based on the comparison, the navigation system10can notify the user39of a change in the accuracy of the instrument52, and can also compensate for the change in the shape of the instrument52, if so desired.

The body122of the sleeve108bcan define a throughbore146. The body122of the sleeve108bcan be composed of a non-ferrous material, such as plastic and/or titanium, for example. The throughbore146of the body122can enable the receipt of the drill bit110within the sleeve108b. Generally, the throughbore146is sized such that the drill bit110can rotate freely within the sleeve108b, and can extend beyond the distal end140of the sleeve108bto contact an anatomy of the patient12.

With reference toFIG. 4, the drill bit110bcan include the tip150and a body152. The tip150can generally be pointed such that the tip150can engage the anatomy of the patient12to remove a selected portion of the anatomy. The body152can include one or more segments154composed of a distinct or unique non-ferrous material with respect to the remainder of the body152of the drill bit110bto enable the navigation system10to identify the trajectory and/or position of the drill bit110.

For example, as shown inFIG. 4, the body152can include a first segment154a, a second segment154b, and a third segment154c. In this example, the first segment154acan be disposed a distance D5from the tip150of the drill bit110b, while the second segment154bcan be spaced apart from the first segment154aby a known distance D6. The third segment154cis spaced a known distance D7apart from the second segment154b. It should be noted that the distances D5, D6, D7can be equal to each other, or each of the distances D5, D6, D7can have a distinct value that can be greater than, less than or equal to the other distances D5, D6, D7, as desired. For example, the distance D5can be less than distance D6and D7, and distance D6can be less than distance D7to enable fine movements of the drill bit110bto be tracked by the tracking system44. Thus, the distances D5, D6, D7between the segments154enable the movement of the drill bit110bto be accurately tracked by the tracking system44, as will be discussed herein. In addition, the number of segments154formed on the body152can enable fine or coarse tracking of the drill bit110b. For example, if fine tracking of the drill bit110bis desired, a large number of segments154can be formed on the body152(not shown).

In this example, each of the segments154can be composed of a first non-ferrous metal or metal alloy, while the remainder of the drill bit110bcan be composed of a second non-ferrous metal or metal alloy. Thus, a different, distinct non-ferrous material can separate each of the segments154. As each of the segments154can be adjacent to a unique non-ferrous material, the position and trajectory of the drill bit110bcan be determined or computed by the coil array controller48. In this regard, the use of the unique segments154of material in the body152of the drill bit110bcan result in a change in the inductance of the electromagnetic coils142due to the varying permeability of the segments154of the drill bit110b. As the electromagnetic coils142can be wound around the body122of the sleeve108b, as best shown inFIG. 5, the movement of the drill bit110bwithin the sleeve108bcan change the current induced in the electromagnetic coils142due to the differing core materials that comprise the segments154, which pass through the electromagnetic coils142during the movement of the drill bit110b, in the exemplary case of receiver electromagnetic coils142. In another example, if the electromagnetic coils142comprise transmitter electromagnetic coils142, then the magnetic field generated or produced by the electromagnetic coils142can vary with the movement of the drill bit110bdue to the change in the permeability of the material comprising the segments154.

In this regard, the amount of current generated by the electromagnetic coils142can increase or decrease based on whether a segment154or the body152of the drill bit110bis positioned within the electromagnetic coil142. Thus, as a length of the drill bit110bis known, and the length, location and material of the segments154of the drill bit110bare known, given the amount of current induced in the electromagnetic coils142during the movement of the drill bit110b, the coil array controller48can compute the position and trajectory of the tip150of the drill bit110bin the patient space, as will be discussed further herein.

With continued reference toFIG. 4, as the drill guide106bcan comprise any suitable guide that enables the user39to direct the motion of the drill bit110bwithin the anatomy, the drill guide106b, will not be described in great detail herein. Briefly, however, the drill guide106bcan comprise the handle156and a cannula158b. The handle156can comprise any suitable graspable or manipulable portion that is configured to enable the manipulation of the drill guide106bby the user39. The cannula158bcan include a proximal end160, a distal end162coupled to the proximal end160via a tube163, with the proximal end160, distal end162and tube163defining an opening or throughbore164therethrough. The cannula158bcan be coupled to the handle156at any desired angle that facilitates the manipulation of the drill104, and generally, can be coupled to the handle156near the proximal end160. The proximal end160of the cannula158bcan define a slot165that can receive an insert166and a stop168.

The insert166can be configured to receive the sleeve108b. The insert166can be threadably coupled to the proximal end160of the cannula158b, or the insert166can be press-fit into the cannula158b. The insert166can enable the sleeve108bto be inserted into and properly aligned in the cannula158b. The insert166can generally extend for a length that enables sleeve108bto be inserted into and visibly aligned within the throughbore164of the cannula158b. The insert166can define threads167to engage the stop168.

The stop168can extend over the insert166at a specified position to provide a safety stop for the drill bit110b. For example, the stop168can extend over the insert166such that connector116of the sleeve108bcan contact the stop168to prevent the continued forward movement of the sleeve108, and thus, the drill bit110b. The stop168can include an actuator172and a housing174.

The actuator172can include threads176that can engage the threads167defined in the insert166of the cannula158. The actuator172can include a biasing element, such as a spring (not specifically shown) to bias the threadeds176between a locked position and an unlocked position. In the locked position, the threads176can engage the threads167to prevent the movement of the stop168. In the unlocked position, the threads176can be released from the threads167of the insert166so that the stop168can be moved relative to the insert166to enable the user39to select a desired depth for the drill bit110bto traverse within the anatomy. Typically, depths can be printed or formed on the exterior of the cannula158b(not shown), and the user39can move the stop168to the desired depth the user39wishes to traverse with the drill bit110b. Thus, the stop168can ensure that the user39drills to a selected depth within the anatomy of the patient12.

The housing174can retain the actuator172. The housing174can protrude above the insert166. Generally, the housing174can be sized such that a portion of the housing174can contact the connector116of the sleeve108bto prevent the advancement of the drill bit110bbeyond the depth set by the actuator172. It should be noted that although the stop168is described herein as including a distinct actuator172and housing174, the stop168could comprise a one-piece assembly, or any other device capable of contacting the connector116of the sleeve108bto prevent the further advancement of the drill bit110b.

The distal end162of the cannula158bcan include a tip178. The tip178can be coupled to the proximal end160of the cannula158, via the tube163, however, the tip178and tube163could be integrally formed with the proximal end160of the cannula158, if desired. The tip178can be tapered to facilitate the passing of the cannula158into an anatomy of the patient12. The tip178can also include barbs or teeth to facilitate the penetration of the cannula158binto the anatomy. The throughbore164can be defined through the cannula158bfor receipt of the sleeve108band drill bit110btherethrough.

In order to assemble the drill104b, the sleeve108bcan be slid over the drill bit110b, such that the electromagnetic coils142can be adjacent to the distal end140of the sleeve108bwhen the drill bit110bis inserted into the sleeve108b. Then, the user39can compress the actuator172of the stop168to move the stop168into a position that corresponds with the desired depth for the drill bit110bto traverse. The user39can release the actuator172to return the stop168to the locked position. The user39can next insert the sleeve108band the drill bit110binto the slot165of the cannula158bof the drill guide106b. Then, the user39can position the tip178of the cannula158binto the selected area of the anatomy, and can actuate the drill104bto advance the drill bit110binto the anatomy of the patient12. The position and trajectory of the drill bit110bcan be tracked by the tracking system44, as will be discussed herein.

Referring now toFIGS. 6-10, additional exemplary instruments52are shown for use with the navigation system10. In this example, the instruments52can be configured to be used with the electromagnetic tracking system44, however, the instruments52could be configured to be used with the optical tracking system44bor a hybrid tracking system (not shown). As the instruments52can be substantially similar to the instruments discussed with regard toFIGS. 2-5, the same reference numerals will be used to discuss the same or similar components. With continuing reference toFIGS. 6-10, the instruments52can include a drill104c(FIG. 6), a drill guide106c(FIG. 6-10) and a trocar298(FIG. 10) that can be used with the drill guide106c. The drill104ccan comprise a sleeve108cand a drill bit110c.

With reference toFIG. 7, the sleeve108ccan include a connector116c, a controller130c, a spring118c, the bushing120and the tracking device58c, each of which can be coupled to the body122of the sleeve108c. As the body122and tracking device58can be substantially similar to the body122and tracking device58discussed with regard toFIGS. 3-5, the body122and tracking device58will not be discussed in great detail herein. With reference toFIG. 8A, the connector116ccan be coupled to the drill guide106c, adjacent to the proximal end124of the body122of the sleeve108c. With additional reference toFIG. 7, the connector116ccan include a throughbore300and a threaded flange302. The throughbore300can be threaded, and can enable the trocar298to be inserted through the sleeve108c, as will be discussed with regard toFIG. 10. The throughbore300can also have a diameter that is sized such that the drill bit110ccan pass therethrough, as shown inFIG. 8B.

With reference toFIGS. 7-8B, the threaded flange302can couple the sleeve108cto the drill guide106cby threadably engaging mating threads306formed on the drill guide110c. It should be noted, however, that any fixation means could be used to secure the sleeve108cwithin the drill guide106c, such as threaded fasteners and the like. The engagement of the threaded flange302with the drill guide106ccan also retain the controller130cwithin the drill guide106c, and can compress the spring118c.

The controller130ccan be coupled to the sleeve108c, and can be slideably retained within the drill guide110cby the connector116c. In this regard, the connector116ccan retain the controller130cwithin a channel C defined in the drill guide110cto enable the controller130cto move relative to the drill guide110cto enable the tracking system44to track the distal end of the instrument52, as will be discussed. As the controller130ccan be substantially similar to the controller130discussed with regard toFIGS. 3-5, only the differences between the controller130and the controller130cwill be discussed herein. The controller130ccan have a proximal end308, a distal end310and can define a bore312. The proximal end308can contact the connector116cwhen the connector116cis coupled to the drill guide106c(FIGS. 8A,8B). The distal end310can contact the stop168of the drill guide110cto control the advancement of the distal end of the instrument52relative to the anatomy of the patient12, as will be discussed with regard toFIG. 9.

The controller130ccan receive the current from the tracking device58, and can transmit a signal indicative of the current of the tracking device58to the navigation probe interface50via at least the cable132. Although not shown, the cable132acan be used to transmit the signal from the tracking device58to the controller130c, as discussed with regard to the controller130ofFIGS. 3-5. It will be understood, however, that although a wired connection is illustrated herein, any suitable technique could be used to transmit the current from the tracking device58to the controller130cand the navigation probe interface50, such as a wireless connection.

The spring118ccan be coupled to the controller130cvia the spring retainer316. The spring118ccan also contact and bias against the tube163of the drill guide106cto enable the compression of the spring118c(FIG. 8A). As the spring118ccan be any suitable biasing member, the spring118cwill not be discussed in greater detail herein. Briefly, however, the compression of the spring118ccan provide a spring force Fs that prevents the undesired movement of the tracking device58. Generally, the spring118ccan be sized such that when the connector116cis engaged with the drill guide110c, as shown inFIG. 8A, the spring118cis compressed to apply a spring force Fs against the distal end310of the controller130c.

With reference toFIG. 7, the drill bit110ccan include the tip150and a body152c. The tip150can be pointed such that the tip150can engage the anatomy of the patient12to remove a selected portion of the anatomy. The body152ccan have a proximal end320and a distal end322. The tip150can be disposed at the distal end322of the body152c. With reference toFIGS. 7-8B, the body152ccan include a first annular flange324and a second annular flange326, each disposed at the proximal end320of the body152c. The first annular flange324can have a diameter D8that is substantially equal to an inner diameter D9of the sleeve108cso that the first annular flange324can rotatably couple the drill bit110cto the sleeve108c(FIG. 8B). The second annular flange326can have a diameter D10that is at least greater than the diameter D9of the sleeve108c, but less than a diameter D11of the throughbore300of the connector116c, and generally about equal to an outer diameter D12of the sleeve108c, such that the second annular flange326can contact the proximal end124of the sleeve108c. The contact between the second annular flange326and the sleeve108ccan cause the sleeve108c, and thus, the controller130cand the tracking device58to move relative to the drill guide106cupon the advancement of the drill bit110c, as will be discussed herein.

With reference toFIGS. 6-10, as the drill guide106ccan comprise any suitable guide that enables the user39to direct the motion of the drill bit110cwithin the anatomy, and can be substantially similar to the drill guide106cdiscussed with regard toFIGS. 3-5, only the differences between the drill guide106ofFIGS. 3-5and the drill guide106cwill be discussed herein, and the same reference numerals will be used to refer to similar components. The drill guide106ccan comprise a cannula158c. The cannula158ccan be illustrated as a two-piece component including a first housing340and a second housing342, however, the cannula158ccan be integrally formed with a one-piece construction. The first housing340can be coupled to the second housing342via one or more mechanical fasteners, however, any suitable fastening system, such as welding, bonding adhesives, rivets, etc., could be employed. The cannula158ccan include the mating threads306and the channel C at the proximal end160. The mating threads306can enable the connector116cto be coupled to the drill guide106c. The channel C can define a path for the linear movement of the controller130c. The channel C can comprise a slot formed in the cannula158c, as shown inFIGS. 7 and 8A, but could comprise any suitable means for controlling the linear movement of the controller130c, such as a rib, etc.

With reference toFIG. 10, the trocar298can be inserted into the throughbore300of the connector116cto prepare the anatomy of the patient12for receipt of the drill bit110c. The trocar298can include a handle350and a body352. The handle350can releasably couple the trocar298to the drill guide106c. In this regard, the handle350can comprise a graspable portion354that can include a threaded receiver356. The graspable portion354can be employed to manipulate the trocar298into engagement with the drill guide106c, by maneuvering threads358on the threaded receiver356into engagement with the threads flange302formed on the throughbore300. The graspable portion354can also include a contact surface354athat can contact the connector116cof the drill guide104cwhen the threads358are engaged with the connector116c.

The threaded receiver356can include the threads358, which can be formed opposite a receiver aperture360. The threaded receiver356can have a diameter D12that can be sized such that the threads358can meshingly engage the threads flange302of the throughbore300. The receiver aperture360can couple the body352to the graspable portion354of the trocar298. The receiver aperture360can be sized such that the receiver aperture360can contact the controller130c, and thus, can cause the controller130cto advance within the drill guide106cuntil the contact surface354aof the graspable portion354contacts the connector116c. Therefore, the advancement of the controller130ccan correspond to an advancement of a tip364of the body352of the trocar298beyond the distal end162of the cannula158c.

The body352of the trocar298can include a proximal end362and a distal end368. The proximal end362can be configured to mate with the receiver aperture360to fixedly couple the body352to the handle350of the trocar298. The proximal end362can include an annular flange367. The annular flange367can have a diameter that is at least greater than the diameter D9of the sleeve108c, but at least is smaller than the diameter D11of the throughbore300of the connector116c(FIG. 8B). The proximal end362can be press fit into the receiver aperture360, for example, however, any appropriate fixation technique could be used to couple the body352to the handle350, such as a mechanical fastener, bonding, welding, mating threads, etc. The distal end368can include the tip364. The tip364can extend from the distal end162of the drill guide106cand can be used to prepare the anatomy for receipt of the drill bit110. The tip364can include multiple teeth366for engagement with the anatomy, as is generally known. The tip364of the trocar298can be configured to engage the anatomy to bore through the skin and tissue of the patient12so that when the trocar298is removed, the drill104ccan be positioned adjacent to the bone of the patient12.

In order to assemble the drill104c, the sleeve108cand the spring118ccan be coupled the controller130c. Then, the sleeve108c, spring118cand the controller130ccan be slid into the channel C of the drill guide106c. With the controller130cinserted into the channel C, the connector116ccan be threaded into engagement with the mating threads306of the drill guide110csuch that the spring118cis compressed. Further, the user39can compress the actuator172of the stop168to move the stop168into a position that corresponds with the desired depth for the drill bit110to traverse. The user39can release the actuator172to return the stop168to the locked position.

With the connector116ccoupled to the drill guide106cand the desired depth set by the user39, the user39can optionally couple the trocar298to the drill guide106c. In order to couple the trocar298to the drill guide106c, the body352of the trocar298can be inserted such that the threads358of the handle350can engage the threads306formed on the throughbore300(FIG. 9). Then, the handle350can be rotated until the contact surface356aabuts the connector116c. This rotation of the handle350can gradually advance the tip364of the trocar298beyond the end of the drill guide106cto prepare the anatomy for receipt of the drill bit110c. Given the diameter of the receiver aperture360, as the tip364is advanced beyond the drill guide106c, the receiver aperture360can apply a force to the proximal end308of the controller130cthat can overcome the spring force Fs to enable the controller130cto move relative to the drill guide106cin the channel C. The relative movement of the controller130ccan be substantially equivalent to a distance traveled by the tip364relative to the end of drill guide106c. Thus, based on the movement of the controller130c, the position of the distal end of the instrument52, in this example the tip364of the trocar298, can be tracked by the tracking system44, as will be discussed herein. The trocar298can be removed from the drill guide106cby unscrewing the handle350from the connector116cof the drill guide106c.

With the trocar298removed from the drill guide106c, the drill bit110ccan be inserted into the drill guide106c. Generally, the drill bit110ccan be inserted until the first annular flange324is disposed within the sleeve108c, with the second annular flange326just contacting the proximal end308of the controller130c, without encountering the spring force Fs, as shown inFIG. 8A. As the user39advances the drill bit110cfurther, the second annular flange326can contact the proximal end308of the controller130c, which can require the user39to apply a force F to the drill104, and thus, the drill bit110c, to overcome the spring force Fs in order to advance the drill bit110cwithin the anatomy of the patient12, as shown inFIG. 9. The advancement of the drill bit110cwithin the anatomy can cause the controller130cto move relative to the drill guide106ca distance Dc, which can be about equivalent to the distance Dttraveled by the drill bit110cbeyond the distal end162of the cannula158c(FIGS. 6 and 9). Thus, the movement of the controller130cwithin the channel C can enable the tracking system44to track the end of the instrument52, in this case the tip150of the drill bit110c, as will be discussed herein.

With reference now toFIG. 11, a simplified block diagram schematically illustrates an exemplary navigation system10for implementing the control module101. The navigation system10can include the tracking system44, the tracking devices58, a navigation control module200and the display36. The tracking system44can comprise an electromagnetic tracking system44or an optical tracking system44b, and will generally be referred to as tracking system44. The tracking system44can receive start-up data202from the navigation control module200. Based on the start-up data202, the tracking system44can set activation signal data204that can activate the tracking device58. The tracking system44can also set tracking data208to the navigation control module200, as will be discussed. The tracking data208can include data regarding the location of the tip or distal end162of the instrument52, which can be determined from the signals received from the controller130of the tracking device58for the instrument52.

When the tracking device58is activated, the controller130can transmit sensor data210indicative of the signal generated by the tracking device58over the cable132ato the tracking system44. Based on the sensor data210received by the tracking system44, the tracking system44can generate and set the tracking data208for the navigation control module200, as will be discussed further herein.

The navigation control module200can receive the tracking data208from the tracking system44as input. The navigation control module200can also receive patient image data100as input. The patient image data100can comprise images of the anatomy of the patient12obtained from a pre- or intra-operative imaging device, such as the images obtained by the imaging device14. Based on the tracking data208and the patient image data100, the navigation control module200can generate image data102for display on the display36. The image data102can comprise the patient image data100superimposed with an icon103of the instrument52, as shown inFIG. 1. The icon103can provide a graphical representation of the position and trajectory of the distal end of the instrument52(i.e., distal end162of the cannula158or tip150of the drill bit110) relative to the anatomy of the patient12. In addition, the icon103can illustrate a starting point of the drill bit110, (i.e., an “X” adjacent to a bone in the anatomy) and can illustrate the trajectory of the drill bit110through the anatomy, (i.e., dashes from the “X”). A current location of the drill bit110can also be displayed by the icon103(i.e., an “O” at the end of the dashes). It should be understood, however, that any suitable symbol, indicia or the like could be employed to graphically represent the location and/or trajectory of the drill bit110relative to the anatomy.

With reference now toFIG. 12, a dataflow diagram illustrates an exemplary control system that can be embedded within the control module101. Various embodiments of the tracking control system according to the present disclosure can include any number of sub-modules embedded within the control module101. The sub-modules shown may be combined and/or further partitioned to similarly determine the position of the drill bit110based on the signal generated by the tracking device58. Inputs to the system can be received from the C-arm16, or even received from other control modules (not shown) within the navigation system10, and/or determined by other sub-modules (not shown) within the control module101(not shown). In various embodiments, the control module101includes the tracking system44that can implement a tracking control module220, and the workstation34that can implement the navigation control module200. It should be noted that the tracking control module220can be implemented by the tracking system44and the navigation control module200can be implemented on the workstation34, however, both of the tracking control module220and the navigation control module200could be implemented on the workstation34, if desired.

The tracking control module220can receive as input the start-up data202from the navigation control module200and sensor data210from the tracking device58. Upon receipt of the start-up data202, the tracking control module220can output the activation signal data204for the tracking device58. Upon receipt of the sensor data210, the tracking control module220can set the tracking data208for the navigation control module200.

The navigation control module200can receive as input the tracking data208and patient image data100. As discussed, the tracking data208can comprise the distal end of the instrument52in patient space. Based on the tracking data208, the navigation control module200can determine the appropriate patient image data100for display on the display36, and can output both the tracking data208and the patient image data100as image data102.

With reference now toFIG. 13, a process flow diagram illustrates an exemplary method performed by the tracking control module220. At decision block250, the method can determine if start-up data202has been received from the navigation control module200. If no start-up data202has been received, then the method loops to decision block250until start-up data202is received. If start-up data202is received, then the method goes to block252. At block252, the tracking system44can generate the activation signal data204. Then, at decision block254the method can determine if the sensor data210has been received. If the sensor data210has been received, then the method goes to block256. Otherwise, the method loops to decision block254until the sensor data210is received.

At block256, the method can compute the location and position of the distal end of the instrument52in patient space based on the sensor data210. In this regard, the sensor data210can provide a location of the tracking device58in patient space. For example, the distal end162of the drill guide106and the depth of the tip150of the drill bit110can be determined based on the movement of the tracking device58relative to the drill guide106. At block258, the method can output the tracking data208. Then, the method can loop to decision block250.

In operation, after the drill guide106has been assembled, the user39can couple the trocar298to the drill guide106c, if desired, or can insert the drill bit110into the drill guide106c. Then, the cable132of the tracking device58ccan be coupled to the navigation probe interface50. The user39can use the user input device38, for example, to instruct the navigation system10to activate the tracking system44. The navigation system10can then send the start-up data202to the tracking control module220. On receipt of the start-up data202, the tracking control module220can output the activation signal data204.

The activation signal data204can induce a signal from the tracking device58. As the signal from the tracking device58corresponds to a unique location in the patient space, the tracking system44can readily determine the location of the tracking device58in the patient space. Thus, as the user39manipulates the instrument52in the patient space, the tracking device58can enable the tracking system44to determine the depth or the position of the distal end of the instrument52, such as the position of the distal end162of the cannula158or the tip150of drill bit110during the surgical procedure.

Based on the location or position of the distal end of the instrument52, the navigation control module200can determine the appropriate patient image data100that corresponds to the determined location of the end of the instrument52, such as the distal end162of the cannula158or the tip150of the drill bit110. The navigation control module200can then output the image data102that comprises the patient image data100with the icon103superimposed on the patient image data100to the display36. Thus, the user39can be provided with a graphical representation of the trajectory and/or location of the instrument52, for example, the distal end162of the cannula158or the tip150and/or trajectory of the drill bit110of the instrument52, relative to the anatomy of the patient12in patient space.

Therefore, the drill104and the drill guide106of the present disclosure can provide a user, such as a surgeon, with an accurate representation of the position and trajectory of the distal end of the instrument52, such as the distal end162of the drill guide106or the tip150of the drill bit110within the drill guide106, during the surgical procedure. The use of a tracking device58that can move relative to the instrument52, in this example, the drill guide106, can enable an accurate depiction of the depth or position and trajectory of the distal end of the instrument52. Alternatively, the tracking device58cin combination with the segments154on the drill bit110bcan enable an accurate depiction of the depth or position of the drill bit110bwithin the anatomy of the patient12, and can also provide an accurate representation of the rotational movement or trajectory of the drill bit110bin the patient space. In addition, the known location of the electromagnetic coils142on the sleeve108of the drill104can update the user39regarding the accuracy of the instrument52. Thus, if the drill guide106or drill bit110is dropped, bent or otherwise damaged during the procedure, the use of the electromagnetic sensors or coils142at a known distance can enable the navigation system10to verify the accuracy of the instrument52throughout the surgical procedure. Further, any changes in the distance between the electromagnetic coils142can be compensated for by the tracking control module220, if so desired.

While specific examples have been described in the specification and illustrated in the drawings, it will be understood by those of ordinary skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure as defined in the claims. Furthermore, the mixing and matching of features, elements and/or functions between various examples is expressly contemplated herein so that one of ordinary skill in the art would appreciate from this disclosure that features, elements and/or functions of one example may be incorporated into another example as appropriate, unless described otherwise, above. Moreover, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular examples illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this disclosure, but that the scope of the present disclosure will include any embodiments falling within the foregoing description and the appended claims.