Patent Publication Number: US-2021177622-A1

Title: Spinal implant system and methods of use

Description:
TECHNICAL FIELD 
     The present disclosure generally relates to medical devices for the treatment of musculoskeletal disorders, and more particularly to a surgical system and method for treating a spine. 
     BACKGROUND 
     Spinal disorders such as degenerative disc disease, disc herniation, osteoporosis, spondylolisthesis, stenosis, kyphosis, scoliosis and other curvature abnormalities, tumor and fracture may result from factors including trauma, disease and degenerative conditions caused by injury and aging. Spinal disorders typically result in symptoms including pain, nerve damage, and partial or complete loss of mobility. 
     Non-surgical treatments, such as medication, rehabilitation and exercise can be effective, however, may fail to relieve the symptoms associated with these disorders. Surgical treatment of these spinal disorders includes correction, fusion, fixation, discectomy, laminectomy and implantable prosthetics. As part of these surgical treatments, interbody devices can be employed with spinal constructs, which include implants such as bone fasteners and vertebral rods to provide stability to a treated region. These implants can redirect stresses away from a damaged or defective region while healing takes place to restore proper alignment and generally support the vertebral members. During surgical treatment, surgical instruments are employed, for example, to facilitate surgical preparation, manipulation of tissue and delivering implants to a surgical site. This disclosure describes an improvement over these prior technologies. 
     SUMMARY 
     In one embodiment, a method for treating a spine is provided. The method comprises the steps of: inserting a surgical instrument into a tissue cavity, the surgical instrument including an image guide oriented relative to a sensor to communicate a signal representative of a position of the surgical instrument relative to the tissue cavity; displaying a selected configuration with a distal end of the surgical instrument in the tissue cavity; tracking movement of the selected configuration in the tissue cavity with a tracking device that communicates with a processor to generate data for display of the movement; and determining a volume of the tissue cavity based on the data. In some embodiments, systems, spinal constructs, implants and surgical instruments are disclosed. 
     In one embodiment, the method comprises the steps of: inserting a distal end of a surgical instrument into an intervertebral cavity, the surgical instrument including a surgical navigation emitter oriented relative to a sensor to communicate a signal representative of a position of the surgical instrument relative to the intervertebral cavity; displaying a sphere with the distal end in the intervertebral cavity from a computer monitor; tracking movement of the surgical instrument in the intervertebral cavity with a tracking device and communicating with a processor to generate data for display of the movement from the computer monitor including generating a plurality of images of the sphere in the intervertebral cavity at discrete time intervals based on movement of the surgical instrument; and determining a volume of the intervertebral cavity based on the data. 
     In one embodiment, the method comprises the steps of: disposing a surgical instrument adjacent to a tissue cavity, the surgical instrument including an image guide oriented relative to a sensor to communicate a signal representative of a position of a distal end of the surgical instrument relative to the tissue cavity; displaying at least one trial with the distal end in the tissue cavity; tracking the surgical instrument relative to the tissue cavity with a tracking device that communicates with a processor to generate data for display of the at least one trial relative to the tissue cavity; and comparing the at least one trial relative to the tissue cavity to determine a volume of the tissue cavity. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more readily apparent from the specific description accompanied by the following drawings, in which: 
         FIG. 1  is a side view of components including a graphical representation of one embodiment of a surgical system in accordance with the principles of the present disclosure; 
         FIG. 2  is a side view of components including a graphical representation of one embodiment of a surgical system in accordance with the principles of the present disclosure; 
         FIG. 3  is a break away view of components including a graphical representation of one embodiment of a surgical system in accordance with the principles of the present disclosure; 
         FIG. 4  is a perspective view of components of one embodiment of a surgical system in accordance with the principles of the present disclosure; 
         FIG. 5  is a graphical representation of a computer display of components of one embodiment of a surgical system in accordance with the principles of the present disclosure disposed with patient anatomy; 
         FIG. 6  is a graphical representation of a computer display of components of one embodiment of a surgical system in accordance with the principles of the present disclosure disposed with patient anatomy; 
         FIG. 7  is a graphical representation of a computer display of components of one embodiment of a surgical system in accordance with the principles of the present disclosure disposed with patient anatomy; 
         FIG. 8  is a graphical representation of a computer display of components of one embodiment of a surgical system in accordance with the principles of the present disclosure disposed with patient anatomy; 
         FIG. 9  is a perspective view of components of one embodiment of a surgical system in accordance with the principles of the present disclosure; 
         FIG. 10  is an axial view of components of one embodiment of a surgical system in accordance with the principles of the present disclosure disposed with vertebrae; 
         FIG. 11  is a lateral view of the components and vertebrae shown in  FIG. 10 ; 
         FIG. 12  is a graphical representation of a computer display of components of one embodiment of a surgical system in accordance with the principles of the present disclosure disposed with an axial view of patient anatomy; 
         FIG. 13  is a lateral view of the components and patient anatomy shown in  FIG. 12 ; 
         FIG. 14  is a graphical representation of a computer display of components of one embodiment of a surgical system in accordance with the principles of the present disclosure disposed with an axial view of patient anatomy; 
         FIG. 15  is a graphical representation of a computer display of components of one embodiment of a surgical system in accordance with the principles of the present disclosure disposed with an axial view of patient anatomy; 
         FIG. 16  is a lateral view of the components and patient anatomy shown in  FIG. 15 ; 
         FIG. 17  is a graphical representation of a computer display of components of one embodiment of a surgical system in accordance with the principles of the present disclosure disposed with an axial view of patient anatomy; 
         FIG. 18  is a graphical representation of a computer display of components of one embodiment of a surgical system in accordance with the principles of the present disclosure disposed with an axial view of patient anatomy; 
         FIG. 19  is a lateral view of the components and patient anatomy shown in  FIG. 18 ; 
         FIG. 20  is a graphical representation of a computer display of components of one embodiment of a surgical system in accordance with the principles of the present disclosure disposed with an axial view of patient anatomy; 
         FIG. 21  is a lateral view of the components and patient anatomy shown in  FIG. 20 ; 
         FIG. 22  is a graphical representation of a computer display of components of one embodiment of a surgical system in accordance with the principles of the present disclosure disposed with an axial view of patient anatomy; 
         FIG. 23  is a lateral view of the components and patient anatomy shown in  FIG. 22 ; 
         FIG. 24  is a graphical representation of a computer display of components of one embodiment of a surgical system in accordance with the principles of the present disclosure disposed with an axial view of patient anatomy; and 
         FIG. 25  is a lateral view of the components and patient anatomy shown in  FIG. 24 . 
     
    
    
     DETAILED DESCRIPTION 
     The exemplary embodiments of a surgical system are discussed in terms of medical devices for the treatment of musculoskeletal disorders and more particularly, in terms of a surgical system and a method for treating a spine. In some embodiments, the systems and methods of the present disclosure comprise surgical navigation and medical devices including surgical instruments and implants that are employed with a surgical treatment, as described herein, for example, with a cervical, thoracic, lumbar and/or sacral region of a spine. 
     In some embodiments, the present surgical system and methods include graphical representation and images of patient anatomy, patient anatomy cavities and volumes, implants including bone graft and/or trials for surgical planning and performing surgical procedures. In some embodiments, the present surgical system is employed with methods that allow a surgeon to determine a size and/or configuration of patient anatomy, patient anatomy cavities and volumes, implants including bone graft and/or trials by projecting an image of patient anatomy, patient anatomy cavities and volumes, implants including bone graft and/or trials in a vertebral space from a computer display employing surgical navigation. 
     In some embodiments, the present surgical system includes a surgical navigation system and one or more processors for generating graphical representation and images of patient anatomy, patient anatomy cavities and volumes, implants including bone graft and/or trials for surgical planning and performing surgical procedures, and is employed with a method of assessing a graft volume utilizing navigated images, as described herein. In some embodiments, one or more processors of the present surgical system execute one or more instructions and/or programming in operation of the surgical navigation system for generating navigated images, for example, navigated projections from surgical instruments. In some embodiments, the surgical system includes a surgical instrument, for example, a funnel having a navigation component. In some embodiments, the present surgical system is employed with a method for calculating an approximate graft volume of one or more patient anatomical cavities. In some embodiments, the present surgical system is employed with a method for determining an amount of intervertebral disc and/or vertebrae preparation. In some embodiments, the present surgical system is employed with a method for determining the amount of intervertebral disc area and/or vertebrae that needs to be removed in connection with surgical planning and performing surgical procedures. In some embodiments, the present surgical system is employed with a method for determining an amount of graft needed to be harvested from a patient and/or from non-patient sources and/or synthetics. In some embodiments, the present surgical system is employed with a method for labeling the navigated projections to indicate graft volume of one or more patient anatomical cavities. 
     In some embodiments, the present surgical system includes a surgical instrument having an image guide oriented relative to a sensor to communicate a signal representative of a position of a surgical instrument relative to a tissue cavity for generating an image of a distal end of the surgical instrument. In some embodiments, the surgical instrument includes a shaft having a linear distal end. In some embodiments, the surgical instrument includes a shaft having an angled distal end. 
     In some embodiments, the present surgical system includes a surgical instrument having a distal end, and one or more processors that execute one or more instructions and/or programming in operation of a surgical navigation system for generating navigated images, for example, a selected configuration, for example, a spherical configuration from the distal end in a tissue cavity. In some embodiments, the surgical navigation system executes one or more instructions and/or programming to initiate volume measurement of a tissue cavity. In some embodiments, the surgical instrument is moved within the tissue cavity and tracked by the surgical navigation system. In some embodiments, movement of the surgical instrument is tracked such that images and/or snap shots of the selected configuration are generated, for example, at discrete intervals such that the surgical navigation system tracks the surgical instrument and generates images of distal end movement. In some embodiments, the surgical instrument is moved along a path within the tissue cavity such that a distal end of the surgical instrument is moved and an image of the distal end of the surgical instrument moving in the tissue cavity is generated in a first dimension, a second dimension and/or a third dimension. In some embodiments, the surgical navigation system executes one or more instructions and/or programming to selectively stop volume measurement upon compilation of the images of the path of the distal end of the surgical instrument. In some embodiments, the surgical navigation system executes one or more instructions and/or programming to calculate a volume of each image, and/or the total volume of the image generated path of the distal end of the surgical instrument. In some embodiments, the captured images of the path of the distal end of the surgical instrument may overlap. In some embodiments, the surgical navigation system executes one or more instructions and/or programming to identify and/or determine the overlap. In some embodiments, the surgical navigation system executes one or more instructions and/or programming to subtract the overlap and calculate a volume of the path of the distal end of the surgical instrument. 
     In some embodiments, the present surgical system includes a surgical navigation system employed with methods for imaging a vertebral space, an intervertebral disc and/or vertebrae axially and/or laterally to determine a volume of a tissue cavity. In some embodiments, the present surgical system is employed with a method for determining a cross section and/or height of the tissue cavity to calculate a volume of the tissue cavity for disposal of an implant, which may include bone graft. In some embodiments, a surgical trial instrument is disposed adjacent the tissue cavity. In some embodiments, the present surgical system includes one or more processors that execute one or more instructions and/or programming in operation of a surgical navigation system for generating navigated images, for example, a trial projection with the surgical trial instrument, which includes an image guide oriented relative to a sensor to communicate a signal representative of a position of a surgical trial instrument relative to the tissue cavity for generating an image of a distal end of the surgical trial instrument. In some embodiments, an image of the surgical trial instrument is displayed relative to imaging of the tissue. 
     In some embodiments, the present surgical system includes a surgical navigation system and one or more processors that execute one or more instructions and/or programming for generating images of a selected configuration, for example, a kidney bean shaped trial projection from an end of the trial instrument. In some embodiments, the trial projection includes a selected volume. In some embodiments, the trial projection is selected from a plurality of alternately sized projections. In some embodiments, one or more trial projections are selected from a volume in a range of about 2.0 cc to about 12.0 cc. In some embodiments, one or more trial projections are selected from a volume in a range of about 2.9 cc to about 10.2 cc. In some embodiments, the one or more processors activate display or graphical representation of the trial projection. 
     In some embodiments, the present surgical system includes a surgical navigation system employed with methods for imaging a surgical trial instrument having a trial projection and a tissue cavity, as described herein, including the step of projecting a trial projection having a first volume, which may be a smaller volume, and comparing the trial projection having the first volume relative to the tissue cavity. In some embodiments, the method includes the step of manipulating the surgical trial instrument for alignment of the trial projection with the tissue cavity to assess if the volume of the trial projection substantially occupies the tissue cavity. In some embodiments, the method includes the step of determining if the trial projection having the first volume sufficiently occupies the tissue cavity and/or if a trial projection having a greater volume is needed. In some embodiments, the method includes the step of manipulating the surgical trial instrument for alignment of a trial projection having a second, larger volume with the tissue cavity to assess if the second volume substantially occupies the tissue cavity. In some embodiments, the method includes the step of determining if the trial projection having the second volume sufficiently occupies the tissue cavity and/or if a trial projection having a greater volume is needed. In some embodiments, the method includes the step of manipulating the surgical trial instrument for alignment of a trial projection having a third, larger volume with the tissue cavity to assess if the third volume substantially occupies the tissue cavity. In some embodiments, the method includes the step of assessing one or a plurality of alternate trial projections having a selected volume for disposal with a tissue cavity. In some embodiments, the method includes the step of determining if the trial projection having a selected volume sufficiently occupies the tissue cavity and/or if the trial projection is too small, too large, and/or may require removal of too much tissue that may compromise the annulus and/or injure the patient. In some embodiments, the features of the present surgical system and methods resist and/or prevent damage or injury to vertebral tissue. In some embodiments, the trial projection is adjustable, for example, to manipulate a height of the trial projection, which may, for example, facilitate determination of a volume of bone graft needed to fill a tissue cavity. 
     In some embodiments, the system of the present disclosure may be employed to treat spinal disorders such as, for example, degenerative disc disease, disc herniation, osteoporosis, spondylolisthesis, stenosis, scoliosis and other curvature abnormalities, kyphosis, tumor and fractures. In some embodiments, the system of the present disclosure may be employed with other osteal and bone related applications, including those associated with diagnostics and therapeutics. In some embodiments, the disclosed system may be alternatively employed in a surgical treatment with a patient in a prone or supine position, and/or employ various surgical approaches to the spine, including anterior, posterior, posterior mid-line, direct lateral, postero-lateral, and/or antero-lateral approaches, and in other body regions. The system of the present disclosure may also be alternatively employed with procedures for treating the lumbar, cervical, thoracic, sacral and pelvic regions of a spinal column. The system of the present disclosure may also be used on animals, bone models and other non-living substrates, such as, for example, in training, testing and demonstration. 
     The system of the present disclosure may be understood more readily by reference to the following detailed description of the embodiments taken in connection with the accompanying drawing figures, which form a part of this disclosure. It is to be understood that this application is not limited to the specific devices, methods, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting. In some embodiments, as used in the specification and including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” or “approximately” one particular value and/or to “about” or “approximately” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It is also understood that all spatial references, such as, for example, horizontal, vertical, top, upper, lower, bottom, left and right, are for illustrative purposes only and can be varied within the scope of the disclosure. For example, the references “upper” and “lower” are relative and used only in the context to the other, and are not necessarily “superior” and “inferior”. 
     As used in the specification and including the appended claims, “treating” or “treatment” of a disease or condition refers to performing a procedure that may include administering one or more drugs to a patient (human, normal or otherwise or other mammal), employing implantable devices, and/or employing instruments that treat the disease, such as, for example, microdiscectomy instruments used to remove portions bulging or herniated discs and/or bone spurs, in an effort to alleviate signs or symptoms of the disease or condition. Alleviation can occur prior to signs or symptoms of the disease or condition appearing, as well as after their appearance. Thus, treating or treatment includes preventing or prevention of disease or undesirable condition (e.g., preventing the disease from occurring in a patient, who may be predisposed to the disease but has not yet been diagnosed as having it). In addition, treating or treatment does not require complete alleviation of signs or symptoms, does not require a cure, and specifically includes procedures that have only a marginal effect on the patient. Treatment can include inhibiting the disease, e.g., arresting its development, or relieving the disease, e.g., causing regression of the disease. For example, treatment can include reducing acute or chronic inflammation; alleviating pain and mitigating and inducing re-growth of new ligament, bone and other tissues; as an adjunct in surgery; and/or any repair procedure. Also, as used in the specification and including the appended claims, the term “tissue” includes soft tissue, ligaments, tendons, cartilage and/or bone unless specifically referred to otherwise. 
     The following discussion includes a description of a surgical system including surgical navigation, surgical instruments, spinal constructs, implants, related components and methods of employing the surgical system in accordance with the principles of the present disclosure. Alternate embodiments are also disclosed. Reference is made in detail to the exemplary embodiments of the present disclosure, which are illustrated in the accompanying figures. Turning to  FIGS. 1-3 , there are illustrated components of a surgical system  10 . 
     The components of surgical system  10  can be fabricated from biologically acceptable materials suitable for medical applications, including metals, synthetic polymers, ceramics and bone material and/or their composites. For example, the components of surgical system  10 , individually or collectively, can be fabricated from materials such as stainless steel alloys, aluminum, commercially pure titanium, titanium alloys, Grade 5 titanium, super-elastic titanium alloys, cobalt-chrome alloys, superelastic metallic alloys (e.g., Nitinol, super elasto-plastic metals, such as GUM METAL®), ceramics and composites thereof such as calcium phosphate (e.g., SKELITE™), thermoplastics such as polyaryletherketone (PAEK) including polyetheretherketone (PEEK), polyetherketoneketone (PEKK) and polyetherketone (PEK), carbon-PEEK composites, PEEK-BaSO 4  polymeric rubbers, polyethylene terephthalate (PET), fabric, silicone, polyurethane, silicone-polyurethane copolymers, polymeric rubbers, polyolefin rubbers, hydrogels, semi-rigid and rigid materials, elastomers, rubbers, thermoplastic elastomers, thermoset elastomers, elastomeric composites, rigid polymers including polyphenylene, polyamide, polyimide, polyetherimide, polyethylene, epoxy, bone material including autograft, allograft, xenograft or transgenic cortical and/or corticocancellous bone, and tissue growth or differentiation factors, partially resorbable materials, such as, for example, composites of metals and calcium-based ceramics, composites of PEEK and calcium based ceramics, composites of PEEK with resorbable polymers, totally resorbable materials, such as, for example, calcium based ceramics such as calcium phosphate, tri-calcium phosphate (TCP), hydroxyapatite (HA)-TCP, calcium sulfate, or other resorbable polymers such as polyaetide, polyglycolide, polytyrosine carbonate, polycaroplaetohe and their combinations. 
     The components of surgical system  10 , individually or collectively, may also be fabricated from a heterogeneous material such as a combination of two or more of the above-described materials. The components of surgical system  10  may be monolithically formed, integrally connected or include fastening elements and/or instruments, as described herein. 
     Surgical system  10  can be employed, for example, with a minimally invasive procedure, including percutaneous techniques, mini-open and open surgical techniques to manipulate tissue, deliver and introduce instrumentation and/or components of spinal constructs at a surgical site within a body of a patient, for example, a section of a spine. In some embodiments, one or more of the components of surgical system  10  are configured for engagement with one or more components of one or more spinal constructs, which may include spinal implants, for example, interbody devices, interbody cages, bone fasteners, spinal rods, tethers, connectors, plates and/or bone graft, and can be employed with various surgical procedures including surgical treatment of a cervical, thoracic, lumbar and/or sacral region of a spine. In some embodiments, the spinal constructs can be attached with vertebrae in a revision surgery to manipulate tissue and/or correct a spinal disorder, as described herein. 
     Surgical system  10  includes a surgical instrument  12 , which is employed with a surgical navigation system  14  and utilized for an intra-operative assessment of a volume of a tissue cavity C, for example, an intervertebral disc space, for determining an implant size and configuration and/or an amount of bone growth promoting material, for example, bone graft for disposal with tissue cavity C in connection with surgical planning and performing surgical procedures, as described herein. In some embodiments, the bone graft may include an agent, which may be disposed, packed, coated or layered within tissue cavity C. In some embodiments, the agent may be HA coating. In some embodiments, the agent may include one or a plurality of therapeutic agents and/or pharmacological agents for release, including sustained release, to treat, for example, pain, inflammation and degeneration. 
     Surgical instrument  12  includes a shaft  20 . In some embodiments, shaft  20  is cannulated. In some embodiments, shaft  20  is configured to inject bone graft, for example, a funnel configuration. In some embodiments, shaft  20  includes a distal end  22 . In some embodiments, distal end  22  includes a linear configuration, as shown in  FIG. 1 . In some embodiments, shaft  20  includes a distal end  22   a  having an angled configuration, as shown in  FIG. 2 . Distal end  22  includes a distal tip  24 . Distal end  22  is configured for movement within tissue cavity C, as described herein. 
     Surgical instrument  12  includes an image guide, for example, a navigation component  58 , as shown in  FIG. 4 , which communicates with surgical navigation system  14  to monitor components of surgical system  10  and patient anatomy under surgical navigation. In some embodiments, navigation component  58  is connected with surgical instrument  12  via an integral connection, friction fit, pressure fit, interlocking engagement, mating engagement, dovetail connection, clips, barbs, tongue in groove, threaded, magnetic, key/keyslot and/or drill chuck. 
     Shaft  20  is positioned a selected distance from vertebral tissue in connection with surgical navigation and for generating an image of distal end  22  and tip  24  for display from a computer monitor, as described herein. Distal end  22  extends a distance measured from a proximal most end surface of shaft  20  in connection with image guidance. In some embodiments, this configuration provides indicia of the size, type and/or position of distal end  22  relative to shaft  20  and/or vertebral tissue. The components of surgical system  10  and surgical navigation system  14  allow a surgeon to determine a size and/or configuration of tissue cavity C for disposal of a selected volume of bone graft, by projecting an image of a selected configuration from tip  24  from a computer display. 
     Surgical navigation system  14  is configured to project an image of a selected configuration, for example, a spherical projection  26  from tip  24 , as shown in  FIGS. 1, 2 and 5 . Projection  26  is displayed from tip  24  having a selected volume V 1  and/or the selected configuration of projection  26  includes selected measurements or indicia in two or three dimensions, for example, length, width, and height to calculate the volume of tissue cavity C for determining an implant size and configuration and/or an amount of bone growth promoting material in connection with surgical planning and performing surgical procedures. In some embodiments, the selected configuration may be polygonal, as shown in  FIG. 3 . In some embodiments, the selected configuration may have alternate configurations, for example, cubed, rectangular cross section, triangular cross section, oblong, barrel shaped, dog bone shaped, t shaped, undulating, staggered and/or offset. In some embodiments, the selected configuration includes a volume selected from a range of greater than zero through 5.0 cc. In some embodiments, the selected configuration includes a volume of 1.0 cc. In some embodiments, spherical projection  26  includes a diameter selected from a range of greater than zero through 20 mm. 
     A graphical image of distal end  22  is displayed from a computer monitor and moved with projection  26  extending therefrom within tissue cavity C in a plane of tissue cavity C. In some embodiments, projection  26  is moved in the plane of tissue cavity C to identify and/or measure tissue cavity C in two or three dimensions, for example, length, width, and height to calculate the volume of tissue cavity C in connection with surgical planning and performing surgical procedures. For example, distal end  22  is moved along a path P, as shown in  FIG. 5 . As distal end  22  is moved within tissue cavity C, projection  26  is displayed from tip  24  to identify and/or measure tissue cavity C in two or three dimensions, for example, length, width, and height of an intervertebral space to calculate the volume of tissue cavity C, as shown in  FIG. 6 . 
     In some embodiments, a graphical image of tip  24  is displayed from a computer monitor and travels in the intervertebral disc space along the anatomical surfaces of vertebral tissue with projection  26  extending therefrom to identify and/or measure a selected area of tissue cavity C, for example, from an axial view of vertebrae, and/or a selected height of tissue cavity C, for example, from a lateral view of vertebrae. In some embodiments, navigation system  14  tracks the movement of surgical instrument  12  with sensors, as described herein, and graphically displays projection  26  from tip  24  along path P in two or three dimensions, for example, length, width, and height of the intervertebral space to calculate the volume of tissue cavity C. In some embodiments, navigation system  14  tracks the movement of surgical instrument  12  with sensors and determines/calculates movement of projection  26  extending from tip  24 , graphically represented from a computer display, with one or more processors of navigation system  14 , which execute one or more instructions and/or programming in operation of navigation system  14 , in two or three dimensions, for example, length, width, and height of the intervertebral space to calculate the volume of tissue cavity C, as shown in  FIG. 5 . 
     Navigation system  14  tracks movement of surgical instrument  12  along path P with projection  26  extending from tip  24  graphically displayed from a computer monitor  66 . Computer monitor  66  displays travel of projection  26  along path P as a continuous path that is selectively moved in an intervertebral disc space to indicate, highlight and/or measure a selected area of the disc space, for example, from an axial view of vertebrae, and/or a selected height, for example, from a lateral view of vertebrae to calculate the volume of tissue cavity C, as shown in  FIGS. 7 and 8 . 
     Navigation component  58  includes an emitter array  62 , as shown in  FIG. 4 . Emitter array  62  is configured for generating a signal to sensor array  60  of surgical navigation system  14 . The signal generated by emitter array  62  includes data points that represent a position and/or orientation of one or more components of surgical system  10 , for example, surgical instrument  12  traveling in tissue cavity C along the anatomical surfaces of vertebral tissue with projection  26  extending therefrom to identify and/or measure a selected area of tissue cavity C. In some embodiments, the signal generated by emitter array  62  includes data points that represent a three-dimensional position of surgical instrument  12  relative to tissue for generating an image of distal end  22  for display from monitor  66 . In some embodiments, emitter array  62  may include a reflector array configured to reflect a signal from sensor array  60 . 
     Emitter array  62  includes four spaced apart arms having a substantially X-shape. Emitter array  62  includes markers, for example, fiducials  64 . Fiducials  64  appear in the image produced by surgical navigation system  14  for use as a point of reference or a measure. Emitter array  62  generates signals representing the position of various reference points of the patient&#39;s anatomy. See, for example, similar surgical navigation components and their use as described in U.S. Pat. Nos. 6,021,343, 6,725,080, and 6,796,988, the entire contents of each of these references being incorporated by reference herein. In some embodiments, fiducials  64  include at least one light emitting diode. In some embodiments, fiducials  64  may include other tracking devices capable of being tracked by sensor array  60 , for example, a tracking device that actively generates acoustic signals, magnetic signals, electromagnetic signals, radiologic signals. In some embodiments, fiducials  64  may be removably attached to emitter array  62 . In some embodiments, one or more of fiducials  64  each include a single ball-shaped marker. 
     Tracking system  72  can include various portions that are associated or included with surgical navigation system  14 . In some embodiments, tracking system  72  can also include a plurality of types of tracking systems, such as, for example, an optical tracking system that includes an optical localizer, such as, for example, sensor array  60  and/or an EM tracking system that can include an EM localizer. Various tracking devices can be tracked with tracking system  72  and the information can be used by surgical navigation system  14  to allow for a display of a position of an item, for example, a patient tracking device, an imaging device tracking device  74 , and an instrument tracking device, for example, emitter array  62 , to allow selected portions to be tracked relative to one another with the appropriate tracking system. In some embodiments, the EM tracking system can include the STEALTHSTATION® AXIEM™ Navigation System, sold by Medtronic Navigation, Inc. having a place of business in Louisville, Colo. Exemplary tracking systems are also disclosed in U.S. Pat. Nos. 8,057,407, 5,913,820, and 5,592,939, the entire contents of each of these references being incorporated by reference herein. 
     Sensor array  60  is located in such a manner to provide a clear line of sight with emitter array  62 , as described herein. In some embodiments, fiducial markers  64  of emitter array  62  communicate with sensor array  60  via infrared technology. Sensor array  60  is coupled to a computer  65 , which may be programmed with software modules that analyze signals transmitted by sensor array  60  to determine the position of each object in a detector space. 
     One or more processors and/or software of surgical navigation system  14  execute one or more instructions and/or programming such that sensor array  60  tracks navigation component  58  attached with surgical instrument  12 . Navigation component  58  includes emitter array  62  that generates a signal to sensor array  60 , which includes data points that represent a position and/or orientation of surgical instrument  12  for generating data points, images and/or snap shots of tip  24  at one or a plurality of time intervals for generating projections  26  in connection with display of path P from computer monitor  66  to calculate the volume of tissue cavity C. In some embodiments, navigation component  58  communicates with sensor array  60  and surgical navigation system  14  to identify positional data points of tip  24  at one or a plurality of time intervals for generating projections  26  in connection with display of path P from computer monitor  66  to calculate the volume of tissue cavity C. See, for example, similar surgical navigation components, imaging and their use as described in U.S. Pat. Nos. 6,021,343, 6,725,080, 6,796,988, 6,940,941, 7,001,045, 7,106,825, 7,108,421, 7,188,998 and 8,842,893, the entire contents of each of these references being incorporated by reference herein. 
     Navigation component  58  generates a signal to sensor array  60 . The signal includes data points representing a position and/or orientation of surgical instrument  12  for imaging position and/or orientation of tip  24  and projection  26  to facilitate capturing and generating imaging of path P for display from computer monitor  66 . In some embodiments, movement of navigation component  58  attached with surgical instrument  12  is tracked by navigation system  14  to generate data points, images and/or snap shots of tip  24  and projection  26  at discrete time intervals. As tip  24  is moved along path P, movement of navigation component  58  attached with surgical instrument  12  is tracked by navigation system  14  using surgical navigation at discrete time intervals, for example, generating data points, images and/or snap shots of tip  24  and displaying projection  26  at positions P 1 , P 2 , P 3 , P 4 , P 5  and P 6 , which are displayed from computer monitor  66  as a continuous path P, as shown in  FIG. 8 . 
     For example, movement of navigation component  58  attached with surgical instrument  12  is tracked by navigation system  14  using surgical navigation to generate data points, an image and/or a snap shot of tip  24  and projection  26  at a first time interval, which is displayed from computer monitor  66  at position P 1 , as shown in  FIG. 5 . At a second time interval, surgical instrument  12  is tracked by navigation system  14  to generate an image and/or a snap shot of tip  24  and projection  26   a  for display from computer monitor  66  at position P 2 . At a third time interval, surgical instrument  12  is tracked by navigation system  14  to generate data points, an image and/or a snap shot of tip  24  and projection  26   b  for display from computer monitor  66  at position P 3 . At a fourth time interval, surgical instrument  12  is tracked by navigation system  14  to generate data points, an image and/or a snap shot of tip  24  and projection  26   c  for display from computer monitor  66  at position P 4 . At a fifth time interval, surgical instrument  12  is tracked by navigation system  14  to generate data points, an image and/or a snap shot of tip  24  and projection  26   d  for display from computer monitor  66  at position P 5 . At a sixth time interval, surgical instrument  12  is tracked by navigation system  14  to generate data points, an image and/or a snap shot of tip  24  and projection  26   e  for display from computer monitor  66  at position P 6 . In some embodiments, surgical instrument  12  is tracked by navigation system  14  to generate data points, images and/or snap shots of tip  24  at one or a plurality of time intervals for projecting projection  26  in connection with display of path P from computer monitor  66  to calculate the volume of tissue cavity C, as described herein. In some embodiments, the time interval may be selected from a range of duration, for example, a time greater than zero seconds through 1.0 seconds. In some embodiments, the time interval includes 0.5 seconds. In some embodiments, the intervals between images and/or snap shots of tip  24  are not based on a time interval, but based on the relative movement of tip  24  from a prior position. In some instances the relative movement which triggers new images is between 0.25 mm and 5 mm. In some embodiments, the relative movement which triggers new images is 1 mm. 
     In some embodiments, one or more processors and/or software of surgical navigation system  14  execute one or more instructions and/or programming to selectively stop tracking of surgical instrument  12  corresponding to generating imaging and/or data points of tip  24  and projection  26 , for example, upon indication, highlight and/or measurement of a selected area of the disc space, for example, from an axial view of vertebrae, and/or a selected height, for example, from a lateral view of vertebrae to calculate the volume of tissue cavity C. 
     In some embodiments, one or more processors and/or software of surgical navigation system  14  execute one or more instructions and/or programming to calculate a total volume V 2  of path P corresponding to the selected area and/or height of the intervertebral disc space, and based on the selected volume of projection  26 . 
     In some embodiments, an algorithm calculates a volume V 2  of tissue cavity C from projections  26 ,  26   a ,  26   b ,  26   c ,  26   d  and  26   e  each having the selected volume V 1 , in connection with determining an implant size and configuration and/or an amount of bone growth promoting material in connection with surgical planning and performing surgical procedures. 
     1) Multiply the number of projections  26  by the selected volume V 1 : 
       6V1=V2 
     In some embodiments, the images of projections  26 ,  26   a ,  26   b ,  26   c ,  26   d  and  26   e  may overlap. In some embodiments, one or more processors and/or software of surgical navigation system  14  execute one or more instructions and/or programming to identify and/or determine the overlap of projections  26 , for example, overlap O 1 , overlap O 2 , overlap O 3 , overlap O 4  and overlap O 5 , as shown in  FIG. 7 . In some embodiments, one or more processors and/or software of surgical navigation system  14  execute one or more instructions and/or programming to subtract overlap O 1 , overlap O 2 , overlap O 3 , overlap O 4  and overlap O 5  from volume V 2  to calculate an actual volume VG. In some embodiments, the present algorithm calculates volume VG of tissue cavity C, in connection with determining an implant size and configuration and/or an amount of bone growth promoting material in connection with surgical planning and performing surgical procedures, as shown in  FIG. 8 . 
     2) To determine a volume VG: 
       V2−(O1+O2+O3+O4+O5)=VG
 
     In some embodiments, distal end  22  and/or tip  24  includes indicia, for example, radiopaque markers. In some embodiments, the markers facilitate viewing and/or identification of the size, configuration, orientation and/or positioning of surgical instrument  12  in space and/or relative to vertebral tissue under x-ray, fluoroscopy, CT or other imaging techniques by surgical navigation system  14 , as described herein. 
     In some embodiments, surgical navigation system  14  includes an image capturing portion  70  that may include an x-ray source or emission portion and an x-ray receiving or image receiving portion located generally or as practically possible 180 degrees from each other and mounted on a rotor (not shown) relative to a track of image capturing portion  70 . Image capturing portion  70  can be operable to rotate 360 degrees during image acquisition. Image capturing portion  70  may rotate around a central point or axis, allowing image data of the patient to be acquired from multiple directions or in multiple planes. Surgical navigation system  14  can include image capturing devices, for example, such as those disclosed in U.S. Pat. Nos. 8,842,893, 7,188,998; 7,108,421; 7,106,825; 7,001,045; and 6,940,941; the entire contents of each of these references being incorporated by reference herein. In some embodiments, surgical navigation system  14  can include medical imaging, for example, C-arm fluoroscopic imaging systems, which can generate three-dimensional views of a patient. The position of image capturing portion  70  can be precisely known relative to any other portion of an imaging device of navigation system  14 . In some embodiments, a precise knowledge of the position of image capturing portion  70  can be used in conjunction with a tracking system  72  to determine the position of image capturing portion  70  and the image data relative to the patient. In some embodiments, one or more processors and/or software of surgical navigation system  14  execute one or more instructions and/or programming in operation of image capturing portion  70  for acquiring and/or capturing data points, images and/or snap shots of tip  24  at one or a plurality of time intervals for projecting projections  26  in connection with display of path P from computer monitor  66  to calculate the volume of tissue cavity C, similar to that described herein. 
     In assembly, operation and use, surgical system  10 , similar to the systems and methods described herein, is employed with a surgical procedure, for treatment of a spine of a patient including vertebrae v and insertion of bone graft into a tissue cavity, for example, an intervertebral disc space C, as shown in  FIGS. 5 and 6 . Surgical system  10  may also be employed with surgical procedures, for example, discectomy, laminectomy, fusion, laminotomy, laminectomy, nerve root retraction, foramenotomy, facetectomy, decompression, spinal nucleus or disc replacement and implantable prosthetics including plates, rods, and bone engaging fasteners. 
     Surgical system  10 , similar to the systems and methods described herein, is employed in connection with one or more surgical procedures for tracking movement of surgical instrument  12 , and acquiring and/or capturing data points, images and/or snap shots of tip  24  at one or a plurality of time intervals with projection  26  extending therefrom in connection with display of path P from computer monitor  66  to calculate the volume of intervertebral disc space C. During a surgery, surgical instrument  12  is configured for disposal adjacent a surgical site such that navigation component  58  is oriented relative to a sensor array  60 , as shown in  FIG. 9 , to facilitate communication between navigation component  58  and sensor array  60 . Distal end  22  of surgical instrument  12  is inserted into intervertebral disc space C. 
     Navigation system  14  executes one or more instructions and/or programming for tracking movement of surgical instrument  12  and acquiring data points that represent a position and/or orientation of surgical instrument  12  for generating data points, images and/or snap shots of tip  24  at one or a plurality of time intervals for generating projections  26  in connection with display of path P from computer monitor  66  to calculate the volume of tissue cavity C, as shown in  FIGS. 5-7 . Surgical instrument  12 , with emitter array  62  attached thereto as described herein, is selectively disposed with intervertebral disc space C. Surgical instrument  12  can be manipulated relative to intervertebral disc space C. Orientation of navigation component  58  relative to sensor array  60  facilitates communication between navigation component  58  and sensor array  60  during the surgical procedure, as described herein. Sensor array  60  receives signals from emitter array  62  to provide information including the data points, as described herein, regarding the configuration, spatial position and/or trajectory of projection  26  relative to intervertebral disc space C. In some embodiments, surgical navigation system  14  provides for real-time tracking of surgical instrument  12 . 
     Emitter array  62  generates a signal including the data points that represent a three-dimensional position of surgical instrument  12  relative to intervertebral disc space C to generate imaging of distal end  22  from an axial view of vertebrae and/or a lateral view of vertebrae. Emitter array  62  communicates the signal including the data points to the processor of computer  65 . The processor measures, calibrates, samples, captures and/or identifies the size, configuration and/or three-dimensional position of distal end  22  in a three-dimensional space and generates an image of the data points of distal end  22  for display from monitor  66 , as described herein. See, for example, the surgical systems and methods described in U.S. Pat. No. 8,571,638, the contents of which being hereby incorporated by reference herein in its entirety. The processor of computer  65  is programed with selected parameters, for example, volume V 1  of projection  26 . 
     Navigation system  14  executes instructions and/or programming to track movement of surgical instrument  12  and generate data points, images and/or snap shots of tip  24  at time intervals of 0.5 seconds and projects projections  26  having a selected volume of 1.5 cc, for example, projections  26 ,  26   a ,  26   b ,  26   c ,  26   d ,  26   e , which are displayed from computer monitor  66  at positions P 1 , P 2 , P 3 , P 4 , P 5  and P 6 , as shown in  FIG. 5 . Surgical navigation system  14  executes instructions to selectively stop data point capture with tip  24 , for example, upon indication, highlight and/or measurement of a selected area of intervertebral disc space C. 
     Navigation system  14  executes instructions and/or programming to calculate a total volume V 2  of path P corresponding to the selected area and height of intervertebral disc space C based on the selected volume of projections  26 , as described herein. The present algorithm calculates a volume V 2  of the selected area of intervertebral disc space C from projections  26 ,  26   a ,  26   b ,  26   c ,  26   d  and  26   e , each having the selected volume V 1 , in connection with determining an implant size and configuration and/or an amount of bone growth promoting material in connection with surgical planning and performing surgical procedures, as shown in  FIG. 7 . 
       V2=6×(1.5 cc)=8.0 cc
 
     The images of projections  26 ,  26   a ,  26   b ,  26   c ,  26   d  and  26   e  overlap such that navigation system  14  executes instructions and/or programming to identify and/or determine the overlap of projections  26 , for example, overlap O 1  (0.25 cc), overlap O 2  (0.25 cc), overlap O 3  (0.3 cc), overlap O 4  (0.3 cc) and overlap O 5  (0.25 cc), as shown in  FIG. 7 . The present algorithm calculates actual volume VG of the selected area of intervertebral disc space C by subtracting overlap O 1 , overlap O 2 , overlap O 3 , overlap O 4  and overlap O 5  from volume V 2  to calculate volume VG. The present algorithm calculates volume VG of tissue cavity C, in connection with determining an implant size and configuration and/or an amount of bone growth promoting material in connection with surgical planning and performing surgical procedures, as shown in  FIG. 8 . 
     
       
         
           
             
               
                 
                   
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     Surgical system  10  employs surgical instrument  12  and surgical navigation system  14 , as described herein, with a method of assessing a graft volume of 6.9 cc of bone graft material for injection via the funnel configuration of distal end  22  with the selected area of intervertebral disc space C, as described herein, in connection with surgical planning and performing one or more surgical procedures. As such, surgical navigation system  14  is employed with a method for calculating an approximate graft volume, for example, 6.9 cc of bone graft material for injection with intervertebral disc space C. In some embodiments, surgical instrument  12  and surgical navigation system  14 , as described herein, are employed with a method for determining an amount of intervertebral disc and/or vertebrae preparation, for example, the amount of intervertebral disc area and/or vertebrae that needs to be removed in connection with surgical planning and performing surgical procedures. In some embodiments, surgical instrument  12  and surgical navigation system  14 , as described herein, are employed with a method for determining an amount of graft needed to be harvested from a patient and/or from non-patient sources and/or synthetics. Upon completion of one or more surgical procedures, the surgical instruments and non-implanted components of surgical system  10  are removed and the incision(s) are closed. 
     In one embodiment, surgical system  10 , similar to the systems and methods described herein, includes a surgical instrument, for example, a trial instrument  212 , as shown in  FIGS. 10-25 . Trial instrument  212  is employed with surgical navigation system  14 , as described herein, and utilized for an intra-operative assessment of a volume of a tissue cavity C 1 , for example, an intervertebral disc space, for determining an implant size and configuration and/or an amount of bone growth promoting material, for example, bone graft for disposal with tissue cavity C 1  in connection with surgical planning and performing surgical procedures, as described herein. 
     Trial instrument  212  includes a shaft  220  having a distal end  222  configured for disposal adjacent tissue cavity C 1 . Trial instrument  212  includes navigation component  58 , as described herein, which communicates with surgical navigation system  14  to monitor components of surgical system  10  and patient anatomy under surgical navigation. Shaft  220  is positioned a selected distance from vertebral tissue in connection with surgical navigation and for generating an image of distal end  222  for display from computer monitor  66 , as described herein. 
     Distal end  222  extends a distance measured from a proximal most end surface of shaft  220  in connection with image guidance. In some embodiments, this configuration provides indicia of the size, type and/or position of distal end  222  relative to shaft  220  and/or vertebral tissue. Surgical instrument  212  includes an image guide, for example, navigation component  58 , as described herein, which communicates with surgical navigation system  14  to monitor components of surgical system  10  and patient anatomy under surgical navigation. Shaft  220  is positioned a selected distance from vertebral tissue in connection with surgical navigation and for generating an image of distal end  222  for display from computer monitor  66 , as described herein. The components of surgical system  10  and surgical navigation system  14  allow a surgeon to determine a size and/or configuration of tissue cavity C 1  for disposal of a selected volume of bone graft by projecting an image of a selected configuration from distal end  222  from a computer display. 
     In some embodiments, three-dimensional scans of selected patient vertebral tissue are captured, via image capture and/or medical imaging as described herein, prior to the surgical procedure. In some embodiments, projection  226  is displayed on a previously captured image of patient vertebrae. Surgical navigation system  14  is configured to project an image of a selected configuration, for example, a trial projection  226  from distal end  222 , as shown in  FIG. 12 . In some embodiments, the selected configuration may have alternate configurations, for example, kidney bean shaped, oval, circular, rectangular, triangular, oblong, barrel shaped, dog bone shaped, t shaped, undulating, staggered and/or offset. 
     Projection  226  is displayed from end  222 . Projection  226  includes a selected volume, a selected surface area and/or the selected configuration of projection  226  includes selected measurements or indicia in two or three dimensions, for example, length, width, and height to calculate the volume of tissue cavity C 1  for determining an implant size and configuration and/or an amount of bone growth promoting material in connection with surgical planning and performing surgical procedures. In some embodiments, projection  226  is selected from a plurality of alternately sized projections  226 . In some embodiments, the selected configuration includes a volume selected from a range of greater than zero through 12.0 cc. 
     In some embodiments, projection  226  is shown relative to a saved image of the intervertebral cavity. The surgeon can view trial instrument  212  and tissue cavity C 1  at various orientations, for example, axial and/or lateral, as described herein. In some embodiments, one or more processors and/or software of surgical navigation system  14  executes one or more instructions and/or programming for tracking movement of trial instrument  212 , and generating data points, images and/or snap shots of distal end  222  with projection  226  displayed from computer monitor  66  for alignment with tissue cavity C 1  and/or to calculate the volume of tissue cavity C 1 . In some embodiments, one or more processors and/or software of surgical navigation system  14  execute one or more instructions and/or programming in operation of image capturing portion  70 , described herein, for acquiring and/or capturing data points, images and/or snap shots of distal end  222  with projection  226  for alignment with tissue cavity C 1  and/or to calculate the volume of tissue cavity C 1 . 
     In some embodiments, projection  226  has, for example, a surface area A 1 , which may be projected initially to compare area A 1  of projection  226  relative to tissue cavity C 1 , as shown in  FIG. 12 . Surgical navigation system  14  tracks movement of trial instrument  212  and generates data points of projection  226  for imaging of projection  226  for display from computer monitor  66 . Projection  226  is manipulated for alignment with tissue cavity C 1  to compare and/or assess area A 1  relative to tissue cavity C 1  to determine that area A 1  sufficiently occupies tissue cavity C 1 , as shown in  FIG. 14 . In some embodiments, projection  226  having area A 1  includes a fixed or a variable height, as described herein, to calculate the volume of tissue cavity C 1 . 
     In some embodiments, a different, for example, larger projection  226  may be viewed for assessment and/or comparison such that a second projection  226   a  having, for example, a surface area A 2  is projected, as shown in  FIGS. 15 and 16 . Surgical navigation system  14  tracks movement of trial instrument  212  and generates data points of projection  226  for imaging of projection  226   a  for display from computer monitor  66 . Projection  226   a  is manipulated for alignment with tissue cavity C 1  to compare and/or assess surface area A 2  relative to tissue cavity C 1  to determine that surface area A 2  sufficiently occupies tissue cavity C 1 , as shown in  FIG. 17 . In some embodiments, projection  226  having area A 2  includes a fixed or a variable height, as described herein, to calculate the volume of tissue cavity C 1 . 
     In some embodiments, a different, for example, larger projection  226  may be viewed for assessment and/or comparison such that a third projection  226   b  having, for example, a surface area A 3  is projected, as shown in  FIGS. 18 and 19 . Surgical navigation system  14  tracks movement of trial instrument  212  and generates data points of projection  226  for imaging of projection  226   b  for display from computer monitor  66 . Projection  226   b  is manipulated for alignment with tissue cavity C 1  to compare and/or assess area A 3  relative to tissue cavity C 1  to determine that area A 3  sufficiently occupies tissue cavity C 1 , as shown in  FIGS. 20 and 21 . In some embodiments, projection  226  having area A 3  includes a fixed or a variable height, as described herein, to calculate the volume of tissue cavity C 1 . 
     In some embodiments, third projection  226   b  is greater than a size of tissue cavity C 1  as it would require removal of tissue that may compromise the annulus and/or injure the patient. As such, a surgeon may select a surface area of projection  226 . In some embodiments, utilizing projections rather than physical trial instruments resists and/or prevents damage or injury to the intervertebral space. 
     In some embodiments, projection  226  is manipulated to adjust a height H of projection  226  to determine and/or calculate, and compare to a height of tissue cavity C 1 , as shown in  FIGS. 22-25 . Surgical navigation system  14  tracks movement of trial instrument  212  and generates data points of projection  226 , as described herein, corresponding to height H of projection  226  for generating imaging of height H of projection  226  for display from computer monitor  66 . Adjusting height H is utilized to determine if the volume of the selected projection  226  sufficiently occupies tissue cavity C 1  and determines a volume VG 2  of bone graft needed to fill tissue cavity C 1 . In some embodiments, an algorithm calculates volume VG 2  of tissue cavity C 1  from projection  226  having an initial surface area and/or height, in connection with determining an implant size and configuration and/or an amount of bone growth promoting material in connection with surgical planning and performing surgical procedures. For example, area A=13.7 cm 2  and height H=10 mm. In some embodiments, the value of VG 2  is displayed on or near projection  226  so that the calculated volume is easily visible. 
     
       
         
           
             
               
                 
                   
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     Surgical system  10  employs surgical instrument  212  and surgical navigation system  14 , as described herein, with a method of assessing a graft volume of bone graft material for injection via a funnel configuration of distal end  222  with the selected area of intervertebral disc space C 1 , as described herein, in connection with surgical planning and performing one or more surgical procedures. As such, surgical navigation system  14  is employed with a method for calculating an approximate graft volume of bone graft material for injection with intervertebral disc space C 1 . In some embodiments, surgical instrument  212  and surgical navigation system  14 , as described herein, are employed with a method for determining an amount of intervertebral disc and/or vertebrae preparation, for example, the amount of intervertebral disc area and/or vertebrae that needs to be removed in connection with surgical planning and performing surgical procedures. In some embodiments, surgical instrument  212  and surgical navigation system  14 , as described herein, are employed with a method for determining an amount of graft needed to be harvested from a patient and/or from non-patient sources and/or synthetics. 
     In some embodiments, projection  226  may include indicia indicating a size of projection, for example, small, medium, large and height. In some embodiments, a selected configuration of projection  226  may conform in size with a vertebral endplate or a partial vertebral endplate, for example, for partial corpectomies. In some embodiments, projection  226  may include indicia indicating an approximate vertebral endplate size, for example, height, length and/or width. In some embodiments, surgical system  10  may be utilized for assessing various anatomical graft volumes, for example, tibial holes, corpectomies, oral, maxillofacial gaps, graft volumes of posterior lateral spaces and/or assessing other anatomic features, foraminal height and/or canal foramen. Upon completion of one or more surgical procedures, the surgical instruments and non-implanted components of surgical system  10  are removed and the incision(s) are closed. 
     It will be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplification of the various embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.