Patent Publication Number: US-11382666-B2

Title: Methods providing bend plans for surgical rods and related controllers and computer program products

Description:
RELATED APPLICATIONS 
     This application is a non-provisional application which claims the benefit of priority as a continuation-in-part from U.S. application Ser. No. 16/183,980 filed on Nov. 8, 2018, which claims priority to provisional application Ser. No. 62/583,851 filed on Nov. 9, 2017. The disclosures of both of the above referenced applications are hereby incorporated herein in their entireties by reference. 
    
    
     FIELD 
     The present disclosure relates to medical devices, and more particularly, surgical robotic systems for bending surgical rods, and related methods and devices. 
     BACKGROUND 
     Spinal fusion is a surgical procedure used to correct deformity of the spine by fusing together the painful part of the spine in order to restrict its motion and relieve painful symptoms. Spinal fusion surgery is commonly utilized to treat abnormal spinal curvatures, such as scoliosis and abnormal kyphosis, for example, degenerative disc diseases, spondylolisthesis, trauma resulting in spinal nerve compression, vertebral instability caused by infections or tumors, and other conditions. 
     Fusion surgery may include the placement of rods and screws using instrumentation and/or the placement of bone graft in between the vertebrae. During surgery, the surgeon may correct the deformity of the spine so as to ensure that the radiographic parameters of the spine in both the sagittal and coronal plane fall within clinically accepted values. While doing so, the surgeon fixes the corrected spine into place using metallic rods. The rods need to conform to the shape of the spine and hence need to be bent accordingly. 
     Currently, devices such as French bender and power bender are utilized in the operation room in order to bend the rods to the desired curvature. However, these devices require cumbersome manual processes to operate. In addition, use of these devices to bend the rod may also introduce notches on the rod, which may decrease the rod&#39;s fatigue life. 
     SUMMARY 
     According to some embodiments of inventive concepts, a system may provide robotic bending used to bend a surgical rod. The system may include a processor, and memory coupled with the processor. The memory includes computer readable program code so that when the computer readable program code is executed by the processor, the processor performs operations including providing a set of transformation points corresponding to respective attachment implants, generating a bend plan for the surgical rod based on the set of transformation points, and generating an image output to render the set of transformation points and the bend plan on a display. 
     According to some other embodiments of inventive concepts, a method may be provided to operate a robotic bending system used to bend a surgical rod. A set of transformation points corresponding to respective attachment implants is provided. A bend plan is generated for the surgical rod based on the set of transformation points. An image output is generated to render the set of transformation points and the bend plan on a display. 
     According to still other embodiments of inventive concepts, a computer program product includes a non-transitory computer readable storage medium having computer readable program code embodied in the medium. When the computer readable program code is executed by a processor of the a system providing robotic bending used to bend a surgical rod, the processor performs operations including providing a set of transformation points corresponding to respective attachment implants, generating a bend plan for the surgical rod based on the set of transformation points, and generating an image output to render the set of transformation points and the bend plan on a display. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate certain non-limiting embodiments of inventive concepts. In the drawings: 
         FIG. 1  illustrates a view of a robotic bending system to automatically bend a surgical rod, according to some embodiments; 
         FIG. 2  illustrates a view of a bending robot of the robotic bending system of  FIG. 1 , according to some embodiments; 
         FIG. 3  illustrates a partially disassembled view of the bending robot of  FIG. 2 , according to some embodiments; 
         FIG. 4  illustrates an internal view of components of a bending robot according to an alternative embodiment; 
         FIG. 5  illustrates components of a rod feeding subassembly of the bending robot of  FIG. 4 , according to some embodiments; 
         FIG. 6  illustrates components of a brake and cutting subassembly of the bending robot of  FIG. 4 , according to some embodiments; 
         FIG. 7  illustrates components of a bending subassembly of the bending robot of  FIG. 4 , according to some embodiments; 
         FIG. 8  illustrates a side view of the components of the bending robot of  FIG. 4 , according to some embodiments; 
         FIG. 9  illustrates components of a rod feeding subassembly for a bending robot according to another alternative embodiment; 
         FIGS. 10A-D  illustrate surgical rods having removable sterile sleeves, according to some embodiments; 
         FIGS. 11A and 11B  illustrate components of a bending robot according to another alternative embodiments; 
         FIG. 12  is a flowchart of a method of operating a bending robot, according to some embodiments; 
         FIGS. 13 and 15  provide illustrations of a Rod Bender System without a drape according to some embodiments; 
         FIGS. 14 and 16  provide illustrations of a Rod Bender System with a drape according to some embodiments; 
         FIG. 17  illustrates an exploded view of a rod bender system according to some embodiments; 
         FIGS. 18A, 18B, and 18C  illustrate examples of mechanical couplings between mechanical and motor housings according to some embodiments; 
         FIG. 19  illustrates an example of a mechanical coupling providing self-centering according to some embodiments; 
         FIG. 20  illustrates a pin that can be used to lock a mechanical coupling according to some embodiments; 
         FIG. 21  illustrates a bottom surface of a mechanical housing according to some embodiments; 
         FIG. 22  illustrates a top surface of a motor housing dissembled from a mechanical housing according to some embodiments; 
         FIG. 23  illustrates an exploded view of a rod bender system according to some embodiments; 
         FIG. 24  illustrates a sterile mechanical housing with a flange and internal side gasket according to some embodiments; 
         FIG. 25  illustrates a rod bender system providing engagement between mechanical and motor housings using a locking mechanism according to some embodiments; 
         FIG. 26  illustrates a rod bender system with a fenestrated drape according to some embodiments; 
         FIG. 27  illustrates springback in a rod after bending according to some embodiments; 
         FIG. 28  illustrates a rod bender system configured to determine springback for a rod according to some embodiment; 
         FIGS. 29A  and B illustrate examples of a rod bender capture probe tip/handle assembly according to some embodiments; 
         FIGS. 30A and 30B  illustrate examples of a rod bender capture probe tip/handle assembly including a stray marker according to some embodiments; 
         FIGS. 31A and 31B  illustrate examples of a rod bender capture probe tip/handle assembly including a stray marker according to some other embodiments; 
         FIGS. 32A, 32B, and 32C  illustrate examples of probe tips that interface with instruments such as the spinal screw of  FIG. 32D  according to some embodiments; 
         FIG. 33  is a screen shot showing transformation points in two orthogonal planes (e.g., the sagittal plane and the coronal plane) corresponding to a patient&#39;s anatomy according to some embodiments; 
         FIG. 34  is a screen shot showing adjustments to the transformation points of  FIG. 33  in the two orthogonal planes according to some embodiments; 
         FIG. 35  is a screen shot showing a use of orthogonal fluoroscope images to construct a bend plan according to some embodiments; 
         FIG. 36  is a screen shot showing merging of multiple bend plans to for a merged plan according to some embodiments; 
         FIG. 37  illustrates use of a bend at the end of the rod to reduce/prevent movement of the rod; 
         FIG. 38  illustrates markings on the rod according to some embodiments; 
         FIG. 39  illustrates a cap on an end of the rod according to some embodiments; 
         FIG. 40  is a block diagram illustrating a controller according to some embodiments of inventive concepts; 
         FIGS. 41-44  are flow charts illustrating operations of the controller of  FIG. 40  according to some embodiments of inventive concepts; and 
         FIGS. 45-53  are exploded views of elements of mechanical housings of bending robots according to some additional embodiments of inventive concepts. 
     
    
    
     DETAILED DESCRIPTION 
     It is to be understood that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the description herein or illustrated in the drawings. The teachings of the present disclosure may be used and practiced in other embodiments and practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
     Referring now to  FIG. 1 , a view of a robotic bending system  10  for automatically bending a surgical rod intraoperatively is illustrated according to some embodiments. The bending system  10  of  FIG. 1  includes a bending robot  100  and may also include a controller unit  102  to control and/or monitor the operation of the bending robot  100  and/or other components or devices. The bending robot  100  includes a rod feeding subassembly  104  to receive, feed, and rotate a surgical rod  106 , a brake subassembly  108  to retain a first portion of the surgical rod  106  at a particular position, and a bending subassembly  110  to bend a second portion of the surgical rod  106  with respect to the first portion of the surgical rod  106  to define a bend angle between the first and second portions of the surgical rod  106 . By feeding and rotating additional sections of the surgical rod  106 , additional portions of the surgical rod can be bent to form a number of different shapes suitable for use in spinal fusion surgery or other procedures. 
     In this example, the controller unit  102  (also referred to as a controller) may include a controller base  112  and a plurality of components, which may be in communication with each other and/or components of the bending robot  100 , as desired. For example, the controller unit may include a camera  114  to monitor the bending robot and/or other aspects of the surgery or procedure, an input device  116  to receive instructions from a user before or during the procedure, and a display device  118  to provide visual information to a user before or during the procedure. The robot  100  and/or controller unit  102  may include one or more processor circuits (not shown) configured to execute machine-readable instructions to operate components of the bending robot  100  or other components or devices. 
     Referring now to  FIG. 2 , a more detailed view of the bending robot  100  of  FIG. 1  is illustrated, according to some embodiments. As shown in  FIG. 2 , the bending robot  100  includes a robot housing  120  that is part of a robot base to house components of the rod feeding subassembly  104 , brake subassembly  108 , bending subassembly  110 , and other components. The rod feeding subassembly  104  includes a rod feeding actuator  124  configured to retain a surgical rod  106  therein, selectively move the surgical rod  106  in a direction parallel to a longitudinal axis of the surgical rod  106 , and selectively rotate the surgical rod about the longitudinal axis of the surgical rod  106 . The rod feeding actuator  124  includes an actuator spindle  134  with a pulley cable  136  wound therearound, and a retaining ring  140  to retain and align the surgical rod  106 . In this example, the retaining ring  140  is sized to hold the surgical rod  106  in place by friction, and to allow the rod to slide through the ring when an appropriate amount of force is applied to the surgical rod  106 . The retaining ring  140  in this example may be selectively replaced with a differently sized retaining ring to accommodate a surgical rod having a different diameter. As will be discussed below, a pulley subassembly (not shown) selectively advances and rotates the surgical rod  106  to position the surgical rod  106  in a correct location and orientation with respect to the brake subassembly  108  and the bending subassembly  110 . It should also be understood that, while this embodiment uses a pulley subassembly, other types of feeding actuator linkages may be used to transfer power from one or more motors to move and/or rotate the rod feeding actuator  124 . 
     The brake subassembly  108  includes a brake housing  142  and a brake actuator  146  configured to receive the surgical rod  106  from the rod feeding subassembly  104 , and selectively fix a first portion of the surgical rod  106  with respect to the brake subassembly  108 . In this embodiment, after the brake actuator  146  fixes the surgical rod  106 , the rod feeding subassembly  104  moves longitudinally back to its original position and may advance and/or rotate the surgical rod  106  further after the brake actuator  146  is released. 
     While the brake actuator  146 , is engaged, the bending subassembly  110  includes a bending actuator  150  that selectively rotates about a first rotational axis perpendicular to the longitudinal axis of the surgical rod  106  to engage a second portion of the surgical rod  106  and bend the second portion of the surgical rod  106  with respect to the first portion of the surgical rod  106  so that the first portion and the second portion of the surgical rod  106  define a first bend angle. To reduce/prevent notching of the surgical rod  106  during the bending process, a pair of roller bearings  154  positioned on either side of the surgical rod  106  form the engagement points between the surgical rod  106  and the bending actuator  150  during the bending process. 
     Referring now to  FIG. 3 , a partially disassembled view of the bending robot  100  of  FIG. 2  is illustrated according to some embodiments. In this example, a mechanical housing  121  includes mechanical components of the rod feeding subassembly  104 , brake subassembly  108 , and bending subassembly  110 , and a motor housing  122  includes additional components of the bending robot  100 , including a first feeding actuator motor  130 , a second feeding actuator motor  132 , a brake actuator motor  148 , a bending actuator motor  172 , and/or additional internal mechanical and/electrical components such as additional linkages and/or electronic processor circuits or other circuits. For example, in some examples a memory coupled to a processor circuit may include machine-readable instructions that, when executed by the processor circuit, cause the processor circuit to cause the rod feeding subassembly  104  to selectively move the surgical rod and selectively rotate the surgical rod  106 , cause the brake subassembly  108  to selectively fix the first portion of the surgical rod, and/or cause the bending subassembly  110  to selectively rotate about the first rotational axis to engage the second portion of the surgical rod  106  and bend the second portion of the surgical rod with  106  respect to the first portion of the surgical rod  106 . 
     The mechanical housing  121  is configured to be removably coupled to the motor housing  122  so that the first and second feeding actuator motors  130 ,  132 , brake actuator motor  148 , and bending actuator motor  172  can selectively operate the rod feeding subassembly  104 , brake subassembly  108 , and bending subassembly  110 , respectively. In this example, the mechanical housing  121  does not include any electrical or electronic components that could be damaged by conventional preoperative or intraoperative sterilization techniques, such as autoclaving, high-temperature steam sterilization, chemical sterilization, or other techniques. Thus, by disposing the non-sterile motor housing  122  in the sterile robot housing  120 , and removably coupling the sterile mechanical housing  121  onto the motor housing  122 , intraoperative sterility can be maintained without needing to expose the electrical and/or electronic components of the bending robot  100  to harsh sterilization techniques that may damage these components and may reduce the useful life of these components. 
     As shown in  FIG. 3 , the rod feeding subassembly includes a first pulley subassembly  126  configured to engage and be driven by the first feeding actuator motor  130 , and a second pulley subassembly  128  configured to engage and be driven by the second feeding actuator motor  132 . A pulley cable  136  is wound around first pulley subassembly  126  and the second pulley subassembly  128 , as well as the actuator spindle  134  of the rod feeding actuator  124 . The first pulley subassembly  126  includes a first pulley transmission input  160  that matingly engages with a first pulley transmission output  164  that is driven by the first feeding actuator motor  130 . The first pulley subassembly  126  also includes a second pulley transmission input  162  that matingly engages with a second pulley transmission output  166  that is driven by the second feeding actuator motor  132 . 
     In this embodiment, the directions of rotation of the first feeding actuator motor  130  and the second feeding actuator motor  132  determine the direction of movement and/or rotation of the surgical rod  106 . For example, to move the rod feeding actuator  124  in a longitudinal direction along a longitudinal rail subassembly  138  toward the brake subassembly  108  and bending subassembly  110 , the first feeding actuator motor  130  rotates counterclockwise and the second feeding actuator motor  132  rotates clockwise. Similarly, to move the rod feeding actuator  124  in a longitudinal direction along the longitudinal rail subassembly  138  away from the brake subassembly  108  and bending subassembly  110 , the first feeding actuator motor  130  rotates clockwise and the second feeding actuator motor  132  rotates counterclockwise. To rotate the actuator spindle  134  in a clockwise direction, the first feeding actuator motor  130  rotates clockwise and the second feeding actuator motor  132  also rotates clockwise. To rotate the actuator spindle  134  in a counterclockwise direction, the first feeding actuator motor  130  rotates counterclockwise and the second feeding actuator motor  132  also rotates counterclockwise. 
     The brake actuator  146  is configured to engage and be driven by the brake actuator motor  148 . The brake actuator  146  includes a worm gear  158  having a brake transmission input  168  that matingly engages with a brake transmission output  170  that is driven by the brake actuator motor  148 . Driving the worm gear  158  causes a brake gear arm  156  to engage and/or disengage the brake actuator  146  to selectively fix or release the surgical rod  106 . In this example, selective operation of the brake actuator motor  148  in a first rotational direction when the brake actuator  146  is in a neutral position causes the brake gear arm  156  to move the brake actuator  146  from the neutral position to an engaged position to selectively fix the first portion of the surgical rod  106  with respect to the brake subassembly  108 . Similarly, selective operation of the brake actuator motor  148  in a second rotational direction opposite the first rotational direction when the brake actuator  146  is in the engaged position causes the brake gear arm  156  to move the brake actuator  146  from the engaged position to the neutral position to selectively release the surgical rod  106 . In this example, the brake subassembly  108  is a brake and cutting subassembly that further includes an internal blade mechanism (not shown), wherein selective operation of the brake actuator motor  148  in the second rotational direction when the brake actuator  146  is in the neutral position causes a blade of the internal blade mechanism to cut the surgical rod  106 . In this example, two internal plates may be slid apart in a reverse scissoring motion, introducing tension to the rod in two different directions and trimming the excess. It should also be understood that an alternative or additional brake actuator linkage may be used in place of or in addition to the worm gear  158  and brake gear arm  156  of the brake subassembly  108 . 
     Similar to the rod feeding subassembly  104  and the brake subassembly  108 , the bending actuator  150  of bending subassembly  110  includes a bending transmission output (not shown) that matingly engages with a bending transmission input  174  that is driven by the bending actuator motor  172 , and that transfers power from the bending actuator motor  172  through a bending actuator linkage (not shown) to drive the bending actuator  150 . Thus, when the sterile mechanical housing  121  is removably coupled to the motor housing  122  in the sterile robot housing  120 , the bending robot  100  is able to automatically bend the surgical rod  106  in real-time in a sterile, intraoperative environment. Following each bend, the previously fixed portion of the surgical rod  106  may be advanced and/or rotated by the rod feeding subassembly  104  and another portion may be fixed by the brake subassembly  108 . The bending subassembly  110  then bends the previously fixed portion of the surgical rod  106 , and so on, until the rod is bent to a desired shape and can be cut and used as part of the spinal fusion surgery or other procedure. 
     Referring now to  FIGS. 4-7 , components of a bending robot  400  according to an alternative embodiment are illustrated. As shown by  FIG. 4 , the bending robot  400  in this embodiment includes a rod feeding subassembly  404 , a brake and cutting subassembly  408 , and a bending subassembly  410 . As shown by  FIGS. 4 and 5 , the rod feeding subassembly  404  includes a rod feeding actuator  424  that is selectively longitudinally movable and rotatable via a first pulley subassembly  426  and second pulley subassembly  428 . A first feeding actuator motor  430  and a second feeding actuator motor  432  transfer power through the first pulley subassembly  426  and second pulley subassembly  428  via a pulley cable  436  to move the actuator spindle  434  along a longitudinal rail subassembly  438  and rotate the actuator spindle. The actuator spindle  434  includes a removable retaining ring  440  to retain and align the surgical rod (not shown) therein. 
     As shown by  FIG. 4 , the brake and cutting subassembly  408  includes a brake housing  442  having a retaining ring  444  similar to the retaining ring  440  of the rod feeding subassembly  404 , to receive and align the surgical rod. A brake actuator  448  is controlled by a brake actuator motor  448  to selectively fix and/or release the surgical rod. As shown by  FIG. 6 , the brake actuator  446  includes a brake gear subassembly including a brake gear  482 . In this example, the brake gear is coaxial with, but independently rotatable with respect to, the main gear of the bending gear subassembly  452 . This arrangement is to conserve internal space, but it should be understood that other mechanical arrangements may be used to achieve the same or similar functionality. In this example, rotating the brake gear  482  causes the brake gear arm  456  to rotate in a first direction from a neutral position, wherein the surgical rod can be freely moved and rotated with respect to through-hole  484 , to an engaged position, wherein the brake gear arm rotates to compress the surgical rod within the through-hole and fix the surgical rod in place. In this embodiment, rotating the brake arm from the neutral position in an opposite direction causes a blade of an internal blade mechanism (not shown) to cut the surgical rod. 
     Referring now to  FIG. 7 , the bending subassembly  410  includes a bending actuator  450  controlled by a bending actuator motor  472  via a bending gear subassembly  452 . A pair of roller bearings  454  are configured to engage the surgical rod when the bending actuator  450  is rotated to bend the surgical rod to a predetermined bend angle. 
       FIG. 8  illustrates a side view of the components of the bending robot  400  of  FIG. 4 . As shown by  FIG. 8 , the components of the bending robot  400  in this example are coupled to an upper support structure  476  and a lower support structure  478  coupled to and spaced apart from the upper support structure  476 , to provide structural support for the components of the bending robot  400  while allowing for easier access to the components of the bending robot  400  for maintenance and repair, for example. 
     Many techniques are available to sterilize and reduce/prevent contamination of a surgical rod being bent in an intraoperative environment. For example, the embodiment of  FIGS. 2 and 3  includes a removable mechanical housing  121  that can be completely sterilized using conventional sterilization techniques without risking damage to the electrical or other components of the separate motor housing  122 . In another example illustrated in  FIG. 9 , a bending robot  900  includes a rod feeding subassembly  904  and a bending subassembly  910  to feed, rotate and bend a surgical rod  906 . In this example, the bending robot  900  includes integrated computing components, including an integrated display  918 , to control the bending robot  900 . 
     In the embodiment of  FIG. 9 , a sterile drape  988  may cover the non-sterilized components of the bending robot  400 , with sterilized components being coupled to the non-sterilized components via magnetic connectors  990 ,  994  of the sterilized components matingly coupling to complementary magnetic connectors  992 ,  996  (e.g., male-female connections) of the non-sterilized components, with motion of the components being transferred through the drape  988 . While magnetic connections are used in this embodiment, it should be understood that other connections, such as a tight-fit mechanism that allows for transferring mechanical motion without compromising the integrity of the drape  988 , may be used. For example, in this and other embodiments, the rotatable components do not require a range of motion of more than 180 degrees. Because of this relatively small range of rotation, using a tight fit mechanism is possible without tearing or otherwise unduly straining the drape  988 . 
     In some embodiments, a sterile surgical rod may be sealed within a sterile sleeve or wrap, which is then bent intraoperatively in a non-sterile environment. In this regard,  FIGS. 10A-D  illustrate surgical rods having removable sterile sleeves as illustrated, according to some embodiments. Referring to  FIG. 10A , a sterile surgical rod  1006  is wrapped in a spiral sterile wrap  1098  material. Following bending of the surgical rod  1006 , the spiral sterile wrap  1098  may be removed and the sterile surgical rod  1006  may be delivered into the sterile intraoperative environment. 
     Similarly,  FIG. 10B  illustrates another sterile surgical rod  1006 ′ having a sterile sleeve  1098 ′ that may be peeled away from the sterile surgical rod  1006 ′ following bending of the sterile surgical rod  1006 ′.  FIGS. 10C and 10D  illustrate a sterile surgical rod  1006 ″ disposed in a sterile flexible shaft  1098 ″, which is sealed at either end by removable caps  1099 . A bending robot in a non-sterile environment may be configured to bend the flexible shaft  1098 ″, thereby bending the sterile surgical rod  1006 ″ within the flexible shaft  1098 ″ without contacting or contaminating the sterile surgical rod  1006 ″. 
     Following the bending process, the sterile surgical rod  1006 ″ may be removed from the flexible shaft  1098 ″ and delivered into the sterile intraoperative environment. In these and other embodiments, the coverings for the sterile surgical rods  1006 ,  1006 ′,  1006 ″ may have a uniform outer diameter, so that different surgical rod diameters may be used without the need for a bending robot to adjust to different outside diameters of the respective coverings. 
       FIGS. 11A and 11B  illustrate components of a bending robot  1100  according to another alternative embodiment. The bending robot  1100  in this embodiment includes a rod feeding subassembly  1104  including a rod feeding actuator  1124 , a brake subassembly  1108  with a brake actuator  1146  having an integrated marking mechanism, and bending subassembly  1110  having a bending actuator  1150  including a pair of roller bearings  1154  configured to engage and bend the surgical rod  1106  without notching or otherwise damaging the surgical rod  1106 . 
     In this example, the rod feeding actuator  1124  is controlled via a feeding gear mechanism  1126 , and the bending actuator  1150  is controlled via a bending gear subassembly  1152 . The brake actuator  1146  is controlled by a manual clamp mechanism  1180  in this embodiment. An integrated marking mechanism, e.g., a retractable marker, may mark points on the rod which, once marked, dictate the shape of the rod as needed to correct an injury, where the marked points indicate the points of the screws along the curve of the bend. This allows for additional control over the shape of the rod, and marking ensures that the surgeon is aware entirely of which screws the rod aligns with for a spinal fusion or other procedure. Alternatively, the surgical rod could be pre-marked, e.g., every five millimeters, with a corresponding number. By displaying these numbers on the screen of a monitor viewable by the surgeon during the procedure, the surgeon can ensure proper positioning of the rods. 
       FIG. 12  is a flowchart of operations  1200  to operate a bending robot, according to some embodiments. The operations  1200  include sterilizing a first housing including a rod feeding subassembly, a brake subassembly, and a bending subassembly (Block  1202 ), and removably coupling the first housing to a second housing including a motor configured to selectively operate the rod feeding subassembly, the brake subassembly, and the bending subassembly (Block  1204 ). The operations  1200  further include retaining a surgical rod in the rod feeding subassembly (Block  1206 ), causing a feeding actuator of the rod feeding subassembly to selectively move the surgical rod in a direction parallel to a longitudinal axis of the surgical rod (Block  1208 ), and causing the feeding actuator to selectively rotate the surgical rod about the longitudinal axis of the surgical rod (Block  1210 ). 
     The operations  1200  further include receiving the surgical rod in the brake feeding subassembly from the rod feeding subassembly (Block  1212 ), and causing a brake actuator of the brake subassembly to selectively fix a first portion of the surgical rod with respect to the brake subassembly (Block  1214 ). The operations  1200  further include causing a bending actuator of the bending subassembly to selectively rotate about a first rotational axis perpendicular to the longitudinal axis of the surgical rod, wherein rotating the bending actuator causes the bending actuator to engage a second portion of the rod and bend the second portion of the rod with respect to the first portion of the surgical rod so that the first portion and the second portion of the surgical rod define a first bend angle. The operations  1200  further include causing a blade of the brake subassembly to selectively cut the surgical rod. 
     Additional operations may include data acquisition, which may occur prior to rod bending and after screws are properly placed via a camera system, which may send the data to the bending robot. Based on the data, the bending robot may perform the operations described above. In another embodiment, the data for bend points can be received through an acquisition camera and a probe that is tracked by the camera, where the probe is touched on the head of each of a plurality of pedicle screws after they have been placed on the patient&#39;s spine. Those points can be used to generate a curve that can be modified and fine-tuned by the surgeon, and that can be used to generate bend points, which can be used by the bending robot to make appropriate bends in the surgical rod. In another example, an intra-operative robot used for screw placement can be used to determine the coordinates of the pedicles and hence can be used to generate a bend curve. In some embodiments, preoperative planning software, such as Surgimap or GMAP, for example, can be used to configure the bend points, which can then be used by the bending robot to bend the surgical rod. Data from the camera may also be used to verify that the robot is operating correctly and/or within predetermined tolerances, and may generate data to instruct the robot to correct for errors in real time. 
     Further discussion of elements of bending robot  110  is provided below with respect to  FIGS. 45-53 . 
       FIGS. 45, 46, and 47  illustrate additional details of a bending subassembly from a mechanical housing of a bending robot. As shown in  FIGS. 45 and 46 , surgical rod  106  is fed into the bending subassembly (also referred to as a bend mechanism) using a rod feeding subassembly (also referred to as a feed carriage). Roller bearings  454  (also referred to as bend rollers) surround respective bend posts  4501  which push the surgical rod  106  to create a precalculated bend in the surgical rod. Roller bearings (bend rollers)  454  roll on respective bend posts  4501  while pushing the surgical rod to reduce damage to the surface of the surgical rod while bending. 
     As shown, the roller bearings  454  and/or bend posts  4051  are attached to a plate of the bending actuator which includes a section of a spur gear referred to as driven gear  4503 . This larger driven gear  4503  is controlled by a smaller spur gear referred to as drive gear  4505 . This mechanism may provide sufficient mechanical advantage to match a torque value used/required to bend a metallic surgical rod. As shown in  FIG. 47 , drive gear  4505  is connected to bending actuator motor  472  via a gearbox  4509  to provide the gear reduction used/required to bend the strongest surgical rods used for spinal correction. Drive gear  4505  and driven gear  4503  may be provided as elements of bending gear subassembly. 
       FIGS. 48 and 49  illustrate additional details of a braking/cutting subassembly from a mechanical housing of a bending robot. The cut axis may use/require more than a thousand times gear reduction to provide a torque used/required to cut the strongest surgical rods used for spinal correction. As shown in  FIGS. 48 and 49 , the cutter arm  4801  may be attached to a section of a bevel gear  4803 . The section of the bevel gear  4803  may be compounded with a pinion bevel gear  4805 , a big spur gear  4807 , a small pinion spur gear  4809 , and a right angle gearbox  4811  to provide sufficient gear reduction in a mechanical coupling with motor  4815  (which may be provided in a motor housing of the bending robot). The cutter arm rotates on a shear plane  4819  perpendicular to the top plate and cuts the rod through a shear mechanism. Rotation in a first direction may thus be provided to cut the rod, while rotation in a second direction may be used to brake the rod (i.e., to hold the rod in a fixed position to prevent lengthwise and rotational movement) while bending the rod as discussed below. 
       FIGS. 50 and 51  illustrate additional details of a rod feeding subassembly from a mechanical housing of a bending robot. The rod feeding subassembly may be used to feed and rotate a surgical rod  106 . The feed/rotate axis may work using a differential drive assembly. A differential drive is achieved using a series of pulleys and a cable  5003 . The cable  5003  is wrapped around the pulleys and a drum  5005  as shown in  FIGS. 50 and 51 . Rotating the drive pulleys  5001   a  and  5001   b  in the same direction rotates the drum  5005  in clockwise and counter-clockwise directions respectively. Rotating the drive pulleys in opposite directions moves the carriage  5009  forward and backward. An advantage of such a mechanism may be that both the feed and rotation of the rod is achieved using just one mechanism. The drive pulleys may be driven by respective motors  5011   a  and  5011   b  through respective gearboxes. Motors  5011   a  and  5011   b  may be provided in a motor housing. The rod  106  is passed through the drum and is held using a collar  5015 . The drum rotates on the carriage, and the collar is threaded into the drum, holding the rod inside the drum. 
     The surgical rod  106  may need to be held firmly while bending it against the bend post and/or roller bearings. This may be achieved using a brake attached to the cutter arm  4801 . The cutter arm  4801  cuts the rod when it rotates in the counter-clockwise direction and brakes the rod when it rotates in the clockwise direction. When the cutter arm  4801  rotates in the clockwise direction, it rotates the brake actuator  5305  which in turn presses the brake arm  5307  on the rod  106  resulting in a braking action. 
     The brake may also be also used during the feed mechanism. In order to feed the entire length of the rod the rod bender may works in the following sequence:
         1. Tighten the rod  106  onto the drum  5005  using the collar  5015 .   2. Feed the rod  106  into the bend subassembly/mechanism for bending operations until the carriage reaches the end of its range of motion closest to the bending subassembly.   3. Brake (e.g., brake arm and brake actuator) holds the rod  106     4. Carriage  5009  slides back on the rod  106 . This can be achieved as the brake is much stronger than the holding collar.   5. Release the brake.   6. Repeat steps 2-5 as needed until rod bending operations are complete.       

     Stated in other words, carriage  5009  may have a limited range of motion, and an effective range of motion may be increased by sliding the carriage back on the rod (i.e., by braking the rod while sliding the carriage back to its starting position most distant from the bending subassembly. 
     According to additional embodiments of inventive concepts, methods may be provided to automatically bend rods using robotic processes intraoperatively, thereby saving time and effort for the surgeons, automating data acquisition, providing/maintaining sterility, and/or maintaining/retaining strength of the rods. 
     Some embodiments of inventive concepts may also provide methods to determine the springback in a rod of a known or unknown material intraoperatively. These methods may allow the user to put any rod in the rod bender without prior knowledge of the material/springback property of the rod. 
     Globus Rod Bender (GRB) systems disclosed herein may provide bending of rods (also referred to as implants or rod implants) for surgical use in patients. Prior techniques may require a surgeon to freehand transform the rod implant(s). Freehand transforming can lead to inconsistencies in the planned bend and/or create weak points in the rod through continuous notching. GRB systems may use patient imaging from screw planning or intra-operative fluoroscopy to bend the implant using an autoclavable mechanical assembly, and the techniques used may allow the system to maintain the sterility of the implant throughout the procedure from bending to placement. 
     Hardware for such GRB systems may be provided as discussed herein with respect to  FIGS. 13 and 14 , which show the Rod Bender System without a drape. 
     The sterilizable rod bender system of  FIG. 13  may include a cart  1301  with motor housing  122  (e.g., as shown in  FIG. 3 ) on the cart  1301 , and with mechanical housing  121  (e.g., as shown in  FIG. 3 ) on motor housing  122 . Motor housing  122  may also be referred to as an embedded motion control system and may include motors, gearboxes and other electronics. Mechanical housing  121  may also be referred to as an autoclavable top assembly and may include mechanical systems that are compatible with high temperature autoclave sterilization.  FIG. 13  shows the cart  1301 , motor housing  122 , and mechanical housing  121  without a drape for ease of illustration.  FIG. 14  shows a drape  1401  sandwiched between the mechanical housing  121  and the motor housing  122  and also covering upper portions of the cart  1301 . Because the drape  1401  covers the motor housing  122  (also referred to as motion control system), the motor housing  122  is not visible in  FIG. 14 . 
     The mechanical housing  121  (also referred to as the autoclavable top assembly) does not include any electrical or electronic components that could be damaged by conventional preoperative or intraoperative sterilization techniques, such as autoclaving, high-temperature steam sterilization, chemical sterilization, etc. Accordingly, the cart  1301  and the motor housing  122  may be covered by the sterile drape  1401 , while the sterile mechanical housing  121  is exposed. Cart  1301  may include wheels  1302   a ,  1302   b , and  1302   c  to facilitate movement. 
       FIG. 14  provides illustration of the Globus Rod Bender system with the drape  1401  installed over the cart  1301  and motor housing  122 . 
       FIG. 15  illustrates an enlarged view of the rod bender system fully assembled, without the drape  1401  engaged over the cart  1301  and motor housing  122 .  FIG. 16  illustrates an enlarged view of the assembled rod bender system, with the drape  1401  engaged over the cart  1301  and over motor housing  122 . 
       FIG. 17  illustrates an exploded view of mechanical housing  121  provided as an autoclavable top assembly, drape  1401 , motor housing  122 , and cart  1301  with an embedded motion control system  200  included in motor housing  122 . 
     The engagement between the mechanical housing  121  (provided as an autoclavable top assembly) and the motor housing  122  with embedded motion control system  200  may work as follows. The mechanical housing  121  may have shafts (also referred to as transmission outputs) with rotary seals. Rotary seals (e.g., radial shaft seals) may be used to seal rotary elements, such as a shaft or rotating bores against fluids, dust, dirt etc. The rotary seals create a barrier between surfaces while allowing for rotary motion transfer. According to some embodiments, there may be four shafts (also referred to as transmission outputs) protruding from (or receiving elements on) the bottom of the mechanical housing  121  to facilitate bending (e.g., bending transmission output of  FIG. 3 ), braking and/or cutting (e.g., brake transmission output  170  of  FIG. 3 ), and feeding and/or rotating the rod (e.g., first and second pulley transmission outputs  164  and  166  of  FIG. 3 , also referred to as rod feeding/rotating transmission outputs). The bottom surface of the mechanical housing  121  (also referred to as a top mechanical assembly) does not have any other holes and may be completely sealed as shown in in  FIG. 21 . 
     A bottom surface of mechanical housing  121  engages with a top surface of motor housing  122  through the drape  1401  and a gasket  2201  on an outer edge of the motor housing  122  embedded in the cart  1301 . As shown in  FIG. 22 , the motor housing  121  embedded on the cart may have 4-shafts (also referred to as transmission inputs)  160 ,  162 ,  168 , and  174  coming out from the top. According to some embodiments, the four shafts may facilitate bending (e.g., bending transmission input  174  of  FIG. 3  corresponding to bending transmission output  176 ), braking and/or cutting (e.g., brake transmission input  168  of  FIG. 3  corresponding to brake transmission output  170 ), and feeding and/or rotating the rod (e.g., first and second pully transmission inputs  160  and  162  of  FIG. 3 , also referred to as rod feeding/rotating transmission inputs, corresponding to first and second pully transmission outputs  164  and  166 ). The shaft housings accommodate for parallel and angular misalignment. The shafts coming out of the top of mechanical housing  121  engage with the shaft housings in the bottom motor housing  122  to facilitate motion transfer from the motors embedded in the motor housing  122  to the mechanisms on the top mechanical assembly  121 . The engagement mechanism can be chosen from a plurality of mechanisms including splines, gears, clutches, and other couplings. 
     The type of engagement between the top plate and bottom plate shafts may be the same or different for all the axes, for example, based on the radial, axial and moment load. This engagement may provide the following characteristics:
         1. Self-centering;   2. Indexing accuracy; and/or   3. Capability to handle parallel, angular or combined misalignments.       

       FIGS. 18A, 18B, and 18C  show examples of self-indexing couplings for the rod bender between the mechanical housing  121  and the motor housing  122 . According to some embodiments, a top coupling structure of  FIG. 18A  may be provided for each of bending transmission output  176 , brake transmission output  170 , first pully transmission output  164 , and second pully transmission output  166 , and a bottom coupling structure of  FIG. 18A  may be provided for each of bending transmission input  174 , brake transmission input  168 , first pully transmission input  160 , and second pully transmission input  162  (or vice versa). According to some other embodiments, a top coupling structure of  FIG. 18B  may be provided for each of bending transmission output  176 , brake transmission output  170 , first pully transmission output  164 , and second pully transmission output  166 , and a bottom coupling structure of  FIG. 18B  may be provided for each of bending transmission input  174 , brake transmission input  168 , first pully transmission input  160 , and second pully transmission input  162  (or vice versa). According to still other embodiments, a top coupling structure of  FIG. 18C  may be provided for each of bending transmission output  176 , brake transmission output  170 , first pully transmission output  164 , and second pully transmission output  166 , and a bottom coupling structure of  FIG. 18C  may be provided for each of bending transmission input  174 , brake transmission input  168 , first pully transmission input  160 , and second pully transmission input  162  (or vice versa). According to some other embodiments, a different coupling types may be used for different couplings (e.g., one of the coupling types from  FIG. 18A  (flat head and corresponding slot),  18 B (pin and slot), or  18 C (male and female splines) may be used to provide couplings between first/second pully transmission outputs and first and second pully transmission inputs, and another of the coupling types from  FIG. 18A, 18B , or  18 C may be used to provide coupling between bending transmission output and bending transmission input and/or between brake transmission output and brake transmission input. 
     As can be seen in  FIGS. 18A, 18B, and 18C , each of the couplings may have a capability of self-indexing. One way to achieve self-centering is to add a central projection to the center of top shafts (analogous to a live center in a lathe machine) as shown, for example, in  FIG. 19  (which illustrates a modification of the coupling of  FIG. 18C ), with a corresponding central depression of the opposing shafts. A central projection may be similarly added to couplings of  FIGS. 18A and/or 18B .  FIG. 19  shows an example how self-centering can be achieved using a spline shaft with a central projection. While the central projection is discussed with respect to the top shaft(s), the central projection may be instead be provided on the bottom shaft with a corresponding central depression on the top shaft. The central projection, for example, may be cone shaped  201 , e.g., conical, paraboloidal, etc., and the corresponding depression may have a shape matching that of the central projection. 
     Another method to engage the shafts of top plate and bottom plate is illustrated in  FIG. 20 . As shown in  FIG. 20 , a spring controlled pin  202  can be placed on the top plate shaft and can be pressed against the bottom plate shaft. If the pin does not fall within the slot, the spring will be compressed. Once the motor starts rotating and the pin falls within the area of the slot  203 , the spring is relaxed and both the shafts start rotating together in order to accomplish motion transfer from the bottom plate to the top plate.  FIG. 18B  shows an embodiment with two such pins that can be spring controlled as discussed above with respect to  FIG. 20 . 
       FIG. 21  illustrates a bottom surface of the mechanical housing  121  including bending transmission output  176 , brake transmission output  170 , first pully transmission output  164 , and second pully transmission output  166 . 
       FIG. 22  shows the cart  1301  with embedded motor housing  122  (Drape not shown), gasket  2201  and with mechanical housing  121  pulled away. As shown in  FIG. 22 , bending transmission input  174 , brake transmission input  168 , first pully transmission input  160 , and second pully transmission input  162  may extend from a top surface of motor housing  122 . 
     Steps of engagement are discussed below with respect to  FIG. 23  which shows an exploded view of the components of the sterilizable rod bender  204 . The top autoclavable mechanical housing  121  may include multiple roller latches  2301  as shown. The cart/motor mount has a movable engagement plate  2303  with a gasket  2305 . Once the mechanical housing  121  is placed on the movable engagement plate  2303  (telescoping platform) and the roller latches  2301 / 205  (also referred to as roller ratchets) are engaged, the gasket  2305  is compressed and the mechanical housing  121  is sealed from the motor housing  122 . In alternative embodiments, the gasket  2305  may be provided on the top (non-moving) surface of motor housing  122  or the bottom surface of mechanical housing  121 . The gasket  2305  may provide a two-fold functionality, that is: providing a seal between motor and mechanical housings  122  and  121  and/or providing that the drape is softly held between a rigid surface and a flexible surface to provide that the drape does not tear with axial or shear loads. Then, the mechanical housing  121  is pushed down which enables the shafts to be engaged with the shaft housings by pushing/puncturing through the drape. Given that the mechanical housing  121  first seals on the gasket and the shafts have rotary seals on them, the sterility may be preserved throughout the assembly procedure. 
     In another embodiment of  FIG. 24 , the mechanical housing  121  positioned on the top assembly may have a flange  2401  with an internal gasket  2403 / 209  to facilitate a seal between the mechanical housing  121  and the motor housing  122  of the bottom assembly after assembly. The gasket  2403  can also serve as a tensioner to provide that the drape  1401  is pulled down along with the top plate prior to drape puncture and shaft engagement. 
     An alternative way to engage the shafts in the mechanical and motor housings  121  and  122  is to place the motor housing on a linear rail and actuate it (up and down), for example, using a cam controlled with a manual lever arm  2503  as shown in  FIG. 25  or a motor. The motor housing  122  may be housed inside a stationary bottom box  2501  and may be actuated up and down, for example, using a lead screw, a cam mechanism, and/or a motor. 
     Operation for embodiments of  FIG. 25  are discussed below.  FIG. 25  illustrates the top assembly  204 , gasket  2201  with bottom shafts  211 , motor housing  212  and lever arm  2503  or  213 . 
     The mechanical housing  121  is placed on the bottom box  2501  and latches  2301  are closed. This provides that the mechanical housing  121  is sealed on the bottom box  2501 . 
     The lever arm  2503  is rotated manually, which raises the motor housing  122 . The motor housing  122  may have the bottom shafts shaped analogous to die cutters to facilitate the cutting of the drape where the upper and lower shafts meet. This leads the shafts of the motor housing  122  to push through the drape and engage with the shafts in the mechanical housing  121 . The motor housing  122  can be locked in this raised position. After the functionality of the rod bender has been achieved, the lever arm  2503  can disengage the motor housing  122  from the mechanical housing  121 . 
     An alternative to pushing/puncturing through the drape is to have a peelable drape  2601  where the shown portion (on top of motor housing  122 ) in  FIG. 26  can have a peel-able top  214  to allow the shafts to engage through the peeled window. Fenestrated drapes can be used for this purpose. Such a design may omit a movable engagement plate. 
     Some embodiments of inventive concepts may provide intraoperative Springback measurement. Bending rods intraoperatively may require knowledge of spring back on the rod in order to bend the rod accurately to a predetermined position. Springback refers to the change in the angle of the rod after it has been released from the bending load. It might be cumbersome to input the material properties of each rod that can potentially be bent by the intraoperative rod bender. 
     As shown in  FIG. 27 , the change in the angle of the rod while bending can lead to erroneous results during bending. In  FIG. 27 , the dashed line indicates a desired bend position to which the rod bender may bend the rod, and the solid line indicates an actual bend position (or springback position) to which the rod returns after the bending force is released from the rod. To achieve the desired bend position, the rod bender may thus need to bend the rod past the desired bend position to compensate for the springback. 
     Hence, methods of the following embodiments may provide ways to determine the springback as a function of angle for a rod of any material.  FIG. 28  illustrates an example of a setup of the rod bending system that may be used to determine springback characteristics (e.g., by determining a springback equation) using a sacrificial rod  106 ′. 
     The sacrificial rod  106 ′ end can have a detachable reflective marker  2811  (also referred to as a reflective sphere), which can be tracked in three-dimensional (3D) space using intraoperative camera  114  or  215 . The camera  114  can be used to determine the position of the reflective marker  2811  or  216  on the sacrificial rod  106 ′ with respect to a known reflective marker array  2815  (also referred to as a tracking array) placed on the rod bending robot  100 . The tracking array  2815  may include at least three reflective markers in a known orientation with respect to the bending robot to allow controller  102  to determine both a position and orientation of bending robot  100  and components thereof. The rod bending robot  100  may need to bend the end of the sacrificial rod  106 ′ to a known angle and once the rod bending robot  100  releases the load on sacrificial the rod  106 ′, the controller  102  and camera  114  can monitor the springback. This may need to occur for two data points (e.g., for two different bend angles) for the rod as discussed below with respect to  FIG. 28  to determine springback characteristics of the rod over a range of bend angles (e.g., using a springback equation). 
     The springback equation for any material can be approximated to a straight line and hence the two different data points for springback on the rod can be used to determine an equation for the material properties of the rod. The two data points can be obtained by choosing two different bend angles at two different positions on the rod and calculating the corresponding springback for each bend angle using the camera  114 . This equation can be used to bend the surgical rod  106  accurately to the required position without having prior knowledge regarding the material of the surgical rod. For example, a sacrificial rod may be provided with the surgical rod where the sacrificial and surgical rods were manufactured together so that both have the same characteristics (e.g., the same diameter, the same material, the same springback characteristics, etc.). Accordingly, springback characteristics of the sacrificial and surgical rods will be the same, and a springback equation developed using the sacrificial rod can be used to accurately bend the surgical rod. The bending system  10  can thus bend the sacrificial rod to two different angles at two different points to determine the springback equation that is used to bend the surgical rod. 
     According to some other embodiments, the spring back equation may be determined by monitoring motor current for the motor used to bend the rod (e.g., bending actuator motor  172 ). 
     In such embodiments, the following operations may be performed. 
     A load may be applied on the sacrificial rod  106 ′ using the bend rotor (e.g., using bending actuator motor  172  to rotate bending actuator  150 ) and bend the sacrificial rod  106 ′ to the desired bend angle. 
     The bend rotor may be rotated back to its original position so as to release the sacrificial rod  106 ′ from bend load. 
     The sacrificial rod  106 ′ will undergo a springback once the bend rotor stops contacting the sacrificial rod  106 ′. 
     Then, the bend rotor may be rotated back until it touches the sacrificial rod  106 ′. This can be determined by monitoring the motor current as there will be a slight spike in motor current (e.g., current to the bending actuator motor  172 ) when the bend rotor touches the sacrificial rod  106 ′. This is the position of the sacrificial rod  106 ′ after the springback. The angular difference between the two points indicates the springback. 
     The above process may need to be repeated at a second position on the sacrificial rod  106 ′ for a different bend angle. 
     Using two springback data points, the springback equation for the sacrificial rod  106 ′ can be calculated and the surgical rod  106  can then be bent accurately using the springback equation determined using the sacrificial rod  106 ′ without requiring any prior knowledge of material properties of the surgical rod  106 . 
     Because the sacrificial and surgical rods may be produced together in a same batch, lot, etc., the springback characteristics of the two may be the substantially the same and/or identical. Accurate calibration of the rod bender may thus be provided for each surgical rod based on actual characteristics of that rod. Accordingly, accuracy of bending may be substantially unaffected by different characteristics of rods produced in different batches, lots, etc. 
     Intraoperative transformation point capture is discussed below according to some embodiments of inventive concepts. 
     The GRB software provides ways to shape a surgical implant device (e.g., rod) based on captured transformation points. These points may be captured using a probe including a probe handle that has an array which can be optically tracked using the camera  114  and a probe tip that attaches to the handle and that fits into a screw or that is used to locate where a rod will be placed. The handle includes its array which is tracked and also an additional moveable stray marker as discussed below with respect to  FIGS. 29A and 29B . 
       FIGS. 29A and 29B  illustrate embodiments of rod bender capture probe tip/handle assemblies according to some embodiments. 
     In  FIG. 29A , the probe  2901   a  includes a probe tip  2907   a  and a tracking array  2903   a  with fixed markers  2905   a   1 ,  2905   a   2 ,  2905   a   3 , and  2905   a   4  and a moveable/stray marker  2911   a . The fixed markers are fixed relative to each other and relative to the probe tip  2907   a  so that a position and orientation of probe tip  2907   a  may be determined using camera  114  to determine positions of the fixed markers in three dimensional space and to thereby determine the position and orientation of the probe tip  2907   a  in the three dimensional space. The moveable stray marker  2911   a  may be used to signal that the probe tip is in the position to be captured by the surgeon pressing the plunger so that the stray marker  2911   a  moves relative to the fixed markers. Upon detecting motion of stray marker  2911   a , controller  102  may determine the position and orientation of probe tip  2907   a  and this position/orientation may be recorded as a transformation point. The stray marker  2911   a  can be actuated by a finger or thumb movement along a defined path in relation to the array  2903   a . When the stray marker  2911   a  is moved (pressed) the system knows to capture the transformation point at the location of the probe tip  2907   a . In  FIG. 29B , the probe  2901   b  includes a probe tip  2907   b , a tracking array  2903   b  (with fixed markers  2905   b   1 ,  2905   b   2 ,  2905   b   3 , and  2905   b   4 ), and a moveable/stray marker  2911   b . The fixed markers are fixed relative to each other and relative to the probe tip  2907   b  so that a position and orientation of probe tip  2907   b  may be determined using camera  114  to determine positions of the fixed markers in three dimensional space and to thereby determine the position and orientation of the probe tip  2907   b  in three dimensional space. The moveable stray marker  2911   b  may be used to signal that the probe tip is in the position to be captured by the surgeon pressing the plunger so that the stray marker  2911   b  moves relative to the fixed markers. Upon detecting motion of stray marker  2911   b , controller  102  may determine the position and orientation of probe tip  2907   b  as a transformation point. This stray marker  2911   b  can be actuated by a finger or thumb movement along a defined path in relation to the array  2903   b . When the stray marker  2917   b  is moved (pressed) the system knows to capture the transformation point at the location of the probe tip  2907   b . If the array is able to rotate around the axis of the handle as shown in  FIG. 29B , the stray marker  2917   b  will still be in the same position because it is in line with the axis of the handle. This embodiment of  FIG. 29B  is shown in greater detail in  FIGS. 30A and 30B . In  FIG. 30A , the plunger is in an initial extended position, and in  FIG. 30B , the plunger has been depressed to indicated that the position and orientation of the probe tip  2907   b  should be captured as a transformation point. 
     It is also possible to have a different type of stray marker that clips onto an array. Such a detachable stray marker may allow any probe or instrument with an array to capture a specific tool location and orientation via the movement of a specific stray marker.  FIGS. 31A and 31B  illustrate a stray marker  3111  attached to the center of a face of array  3103  including fixed markers  3105 - 1 ,  3105 - 2 ,  3105 - 3 , and  3105 - 4 . When the button  3117  is pressed, the probe tip location and orientation can be captured. 
     The Probe tip may be made to interface with a screw or other rod holding implant, so that when the probe tip is engaged with a compatible screw a precise location and orientation of the screw/head can be determined. As shown in  FIG. 32D , for example, a spinal implant screw  3251  may have a threads  3257  configured to secure the screw into bone and a tulip head  3255  configured to receive a surgical rod  106 . The tulip head  3255  may have a U-shaped recess  3259  configured to receive the surgical rod  106  and a threaded recess configured to receive a locking cap  3261  to lock the rod into place. Locking cap  3261 , for example, may be threaded to screw into an upper portion of the tulip head  3255  after placing the rod. 
     As shown in  FIG. 32A , the probe tip  3207   a  may be paddle shaped with a cylindrical center  3208   a  which interfaces with the center of the screw&#39;s tulip head (before placement of the rod and locking cap). The probe geometry of  FIG. 32A  may allow it to be used to manipulate the tulip head  3255  to better represent the direction which the rod would be facing. Because the paddle portion of probe tip  3207   a  aligns with the U-shaped recess of the tulip head and the cylindrical portion aligns with the opening for the locking cap, when properly placed, the probe tip  3207   a  will align with both the center of the tulip head and a direction of the rod through the tulip head allowing determination of both the location and alignment of the U-shaped opening. 
     As shown in  FIG. 32B , a side loading probe  3207   b  may interface with different connectors or screws that cannot be accessed from the top. The hook  3210   b  of the probe would represent the rod and allow the capture of a specific trajectory without requiring top access.  FIG. 32C  shows the side loading probe  3207   b  interfacing with a connector  3221   c  (with hook  3210   b  inside connector  3221   c ). 
     Software and/or control components of the rod bending system  10  are discussed below according to some embodiments of inventive concepts. 
     Software and/or control components (e.g., controller  102 ) of some embodiments of inventive concepts may provide a way to overlay captured transforms over patient images using display  118 . Utilizing the transformation points, the controller/software may control the bending robot  100  to shape an implant for operational use. Additionally, prior to shaping the implant, the user (e.g., the surgeon) may also label transformation points to correspond to the patient&#39;s anatomy where bends may be needed (e.g., the S1-S4 vertebrae), a feature illustrated in  FIG. 33 . As shown in  FIG. 33 , four transformation points are illustrated in the upper and lower views taken in orthogonal planes/views (e.g., the Sagittal and Coronal planes), and these transformation points are identified as the first, second, third, and fourth sacral vertebrae (i.e., S1, S2, S3, and S4). These transformation points may be optically determined using camera  114  to determine probe tip placements in respective screws or other implants, for example, as discussed above with respect to  FIGS. 29A, 29B, 30A, 30B, 31A, 31B, 32A, 32B, and 32C . Because the transformation points may be determined based on the existing spinal alignment, the user (e.g., surgeon) may adjust the transformation points on display  118  before initiating rod bending as indicated by the circle and arrow at the left most transformation point in each of the views of  FIG. 33 . 
     Controller/software operations to acquire transformation points may include pre-operative and/or intraoperative workflows, for example, as discussed below. 
     Intra-Operative acquisition of transformation points is discussed below. 
     To track rod attachment point acquisition, the controller/software may have the ability to automatically capture rod attachment points at respective screws (after screw placement), including the screw head orientation and position. Probes used to capture such rod attachment points are discussed above. Using the controller/software, the user (e.g., surgeon) can then send this captured information to the rod bender (e.g., rod bending robot) to shape the rod implant for clinical use. 
     The controller/software can provide a way to optically capture attachment points using camera  114 , for example, based on a position of a probe in camera space and/or a position of a probe with respect to a patient fixation tracking array. The controller/software may track probe position based on information from camera  114  and capture a current position/orientation of the probe tip responsive to stray movement (e.g., using a movable stray marker/reflector as discussed above with respect to  FIGS. 29A, 29B, 30A, 30B, 31A and/or 31B ) relative to the camera  114  or responsive to user interface (UI) action (e.g., via a touch sensitive portion of display  118 , a physical button, a pedal, etc.). The user (e.g., surgeon) is also able to make adjustments in cardinal directions of transformation points before bending/shaping the implant, as shown in  FIG. 34 . In  FIG. 34 , initial transformation points have been input (e.g., optically captured) for screws in the first, second, third, and fourth sacral vertebrae (i.e., S1, S2, S3, and S4), with the transformation point for the first sacral vertebrae S1 selected for adjustment as indicated by highlighting “S1” on the right of the screen and by displaying a circle around the S1 transformation point in both of the sagittal and coronal views. In this configuration, the user (e.g., surgeon) can adjust the location of the S1 transformation point in the sagittal view and/or coronal view to affect movement of the S1 transformation point in three dimensions. Any of the other transformation points (e.g., the S2, S3, and/or S4 transformation points) may be selected and adjusted in a similar manner. Adjustment may be performed by controller/software responsive to user input through touch sensitive portions of display  118 , and/or responsive to user input through a separate user input interface (e.g., a mouse, joystick, track ball, keypad, etc.). For example, the user may touch the respective label (e.g., “S1”, “S2”, “S3”, or “S4”) on the right side of display  118  to select the respective transformation point, or the user may touch a transformation point in either the sagittal view or coronal view to select the transformation point. Once a transformation point is selected, the user may touch and drag the selected transformation point in the sagittal view to adjust a position of the transformation point in the sagittal plane, and/or the user may touch and drag the selected transformation point in the coronal view to adjust a position of the transformation point in the coronal view. 
     According to some embodiments, fluoroscopy can be used for attachment point acquisition (also referred to as capture). The GRB can use fluoroscopic images to construct a bend plan for the rod intraoperatively. The user (e.g., surgeon) may capture fluoroscopy images of the patient. The controller/software will automatically locate and label attachment points for the rod based on screw placement as shown in  FIG. 35 . The user (e.g., surgeon) will be able to view these points in the sagittal and coronal views as shown in  FIG. 35  and make adjustments as useful/necessary to obtain the desired bend plan for the rod. 
     Once the user (e.g., surgeon) reviews and accepts the bend plan, the GRB will shape the rod implant for surgical use. 
     Shaping the rod implant based on screw location in fluoroscopy is illustrated in  FIG. 35 . In  FIG. 35 , display  118  provides two orthogonal fluoroscopic images with  5  spinal screws identified for placement of surgical rod  106 , and the 5 screws are identified as screws for the first, second, third, fourth, and fifth sacral vertebrae (i.e., S1, S2, S3, S4, and S5). The controller/software may automatically identify the five illustrated initial transformation points for the rod based on locations of the respective screws and create an initial bend plan for the rod based on the initial transformation points. The user (e.g., surgeon) may then select a transformation point on the display  118  for adjustment (e.g., by selecting/touching the respective label on the right of display  118 , or by selecting/touching the respective transformation point in the sagittal or coronal view). In  FIG. 35 , the transformation point corresponding the S1 vertebrae is selected for adjustment as indicated by the box highlighting the label “S1” on the right side of display  118  and the circle (with arrows) surrounding the respective transformation point. The user may select and adjust one or more of the transformation points to provide a modified bend plan for the rod before initiating actual rod bending. Selection and/or adjustment may be provided as discussed above with respect to  FIG. 34 . 
     Pre-Operative operations are discussed below according to some embodiments of inventive concepts. 
     According to some embodiments, a screw plan may be used to generate a bend plan for a rod. The controller/software may allow the surgeon to plan a shape (also referred to as a bend plan) for the surgical rod implant based on attachment point placement created using the ExcelsiusGPS system. In such embodiments, pre-operative imaging (e.g., CAT scan imaging, MRI imaging, fluoroscopic imaging, etc.) may be used to provide images of the patient&#39;s anatomy (e.g., spine) in different (e.g., orthogonal) planes (e.g., sagittal and coronal planes) on display  118 . Controller/software may then accept user input (e.g., using touch sensitive portions of display  118 ) to place virtual screws for the procedure on the display to provide the screw plan for the procedure. After placement of the virtual screw implants, the controller/software can automatically identify rod placement points for each virtual screw to provide initial transformation points for an initial rod bend plan, and the user can modify one or more of the initial transformation points to provide modified transformation points used to generate a modified bend plan for the rod. Once the user approves the bend plan, the user can send the bend plan (e.g., surgical shape) to the rod bender and shape the rod implant to fixate to attachment points of the screws. 
     Generation of a rod bend plan based on pre-operative virtual screw placement may be similar to intra-operative bend planning discussed above with respect to  FIGS. 33, 34 , and  35  that are based on actual screw placement. With both intra-operative and pre-operative bend planning, initial transformation points for an initial bend plan for the rod may be generated based on respective (real or virtual) screw placements, and the user may adjust one or more of the initial transformation points to generate the final bend plan for the rod. The imaging used for virtual screw placements may be similar to that of  FIGS. 33, 34 , and/or  35  except that the images of the virtual screws are added by the controller/software based on user input (as opposed to being included as a part of the original imaging. 
     If the surgeon does not use the GPS to insert the actual screw implants, the controller/software can still shape the surgical implant based on virtual/real attachment/screw point placement with other means, provided the plan is produced in proprietary format. After placing the real/virtual screw implants, the user can send the bend plan to the GRB, which will then shape the rod to allow fixation to the screw attachment points. 
     Merging of plans between pre-operative and intraoperative plans may also be provided according to some embodiments of inventive concepts. The controller/software may provide a way to combine two or more plans to form a merged plan. The user will be able to assign weights to both predicate plans that are used to calculate the merged bend plan, depending on the accuracy of each of the desired bend locations, as shown, for example, in  FIG. 36 . 
     Whether using placement of actual or virtual screws to generate a bend plan for a surgical rod, controller  102  may generate the bend plan to both: 1) fit points on the rod to respective transformation points (corresponding to respective attachment implants, e.g., screws); and 2) orient a trajectory of the rod at each transformation point to match a trajectory of the respective attachment implant (e.g., a trajectory/direction of a tulip head of the respective screw). Accordingly, the bend plan for the rod may consider both the positions of the attachment implants (e.g., screws) and the orientations of the attachment implants (e.g., orientations of tulip heads of the screws). 
     According to some embodiments of inventive concepts, software-based implant shaping verification may be provided. 
     After shaping the implant, the controller/software may provide verification that the implant is properly shaped using one or more approaches discussed below. 
     Tip verification may be provided as discussed below after completion of rod bending but before cutting the rod. 
     Using a tracked array  2815  on a base of the system, the user may be able to touch a tip of a tracked instrument to the tip/end of the rod implant after completion of bending but before cutting the rod. A numerical estimate of the accuracy of the bend may be provided on display  118  to the user for shape verification. Based on the intended bend plan, the controller/software can determine a planned/calculated position of the tip/end of the rod after completion of all bends, and the planned/calculated position of the tip/end of the rod can be compared with the actual position of the tip/end to generate the numerical estimate of accuracy of the rod shape. A single data point may thus be used to provide the numerical estimate of the overall accuracy of the rod shape. 
     Shape verification may be provided as discussed below after completion of rod bending but before cutting the rod. 
     Using a tracked array  2815  on the base of system, the user may be able to run a circular probe over the length of the implant and sample probe locations corresponding to respective rod locations to generate a numerical estimate of an accuracy of the rod shape after completion of rod bending but before cutting the rod. Based on the intended bend plan, the controller/software can determine planned/calculated positions along the length of the bend plan for the rod, and these planned/calculated positions may be compared with the actual sampled probe locations at corresponding positions along the length of the actual bent rod to generate the numerical estimate of the accuracy of the rod shape. A plurality of data points may thus be used to provide the numerical estimate of the overall accuracy of the rod shape. 
     Tool verification may be provided as discussed below after completion of rod bending and after cutting the rod. 
     Using two tracked instruments/probes, the user may touch both ends of the implant to verify shape accuracy using calculations based on where the tips of the rod implant are in relation to the center of the rod implant after completion of bending and before/after cutting. Based on the intended bend plan, the controller/software can determine a planned/calculated distance between the two tips/ends of the rod, and an actual distance between the two tips/ends of the actual bent rod can be determined based on an optical determination of the actual tips/ends of the bent rod using camera  114  and the tracked probes. 
     Placement of the rod implant is discussed below according to some embodiments of inventive concepts. 
     After checking/ensuring accuracy of the rod implant shape/properties (e.g., bends, length, etc.), the user may cut the rod implant and then place the implant into the tulips of the screw heads and secure the rod in each screw using a respective locking cap. 
     After the automatic rod bender has bent the rod, it may be difficult for the user (e.g., surgeon) to know the proper orientation of the rod with respect to the spine. Even after the user (e.g., surgeon) is able to determine the proper orientation of the rod, the user (e.g., surgeon) may need to fix an end of the rod to the first/last screw to provide/ensure that the rod does not slide while fixing it to the other/remaining screws. The fixing of the rod to the last/first screw may also help to provide/ensure that the rod falls accurately where it needs to be without the rod sliding on the screws. 
     The following approaches may help the user (e.g., surgeon) to orient the rod  106  with respect to the spine and/or to fix the rod  106  on the first/last screw. 
     According to some embodiments, an extra bend  3801  may be added to the rod  106  before cutting as shown in  FIG. 37 . 
     The extra bend  3701  can be added to the end of the already bent rod  106  using the automatic rod bender. The extra bend  3701  can be used both to assist the user (e.g., surgeon) to orient the rod and/or to reduce/prevent sliding of the rod during/after the procedure as shown  217 , for example, in  FIG. 37 . As shown in  FIG. 37 , the extra bend  3701  may stop the bent rod  106  from sliding to the left through the tulip head  3703  of screw  3705  while securing the rod to other screws (not shown). The extra bend can also assist in proper placement of the rod relative to the first/last screw  3805  by providing a “stop” against the tulip head  3703  when the rod is properly positioned. In addition, a direction of the extra bend  3701  can be used to indicate a proper rotation of the rod relative to screw  3705 . For example, the portion of the rod between the extra bend  3701  and rod end  3711  may be configured to lay horizontal (or vertical) when the rod is in a proper rotational position. By providing that portions of the rod between the extra bend  3701  and the end of the rod  3711  are configured to extend in a direction that is orthogonal with respect to sides of the U-shaped opening in the tulip head, the bend may act as a “stop” with respect to rod  106  sliding to the left in  FIG. 37 . 
     According to some embodiments, markings  3821  on the rod  106  may be used to orient the rod  106  as shown in  FIG. 38 . Many spinal rods may come with a distinct dotted or solid midline marking  3821 , as illustrated in  FIG. 38 . The following operations can be followed to use the midline  3821  as an orientation marker. 
     According to some embodiments, the rod  106  may be inserted into the rod bender (e.g., into rod feeding subassembly  104 ) in a way that the midline  3821  faces up. There can also be a central line on the rod bender to help the user match the rod to this line. This may be referred to as the home position of the rod  106  prior to initiating bending. 
     According to some embodiments, the rod bender controller/software may know precisely the total rotation the rod needs to go through to achieve the 3D bending. 
     At the start of bending operations the rod bender can rotate the rod to such a position such that after the rod has been completely bent by the rod bender, the midline faces up when oriented as intended for fixation to the patient. 
     According to some embodiments, a biocompatible cap  3901  may be provided at the end of the rod  106  as shown in  FIG. 39 . 
     A biocompatible cap  3901  as illustrated in  FIG. 39  can be placed at the end of the rod  106  to help the user (e.g., surgeon) determine the orientation of the rod  106  with respect to the spine after the rod  106  is bent and at the same time reduce/prevent sliding of the rod on the polyaxial screw head. The cap may need to be placed on the front end of the rod  106  (i.e., the end that is first fed into the rod feeding subassembly  104  and the bending subassembly  110 ) as the other end of the rod is cut. The cap can be threaded or pressfit to the end of the rod. After the rod has been fixed to the spine, the cap can be removed. As mentioned with respect to embodiments discussed above, the controller/software may know exactly the amount of rotation that the rod has to go through to facilitate 3D (three dimensional) bending. After the rod is inserted into the rod bender (but before initiating bending), the cap can be placed in such a way that a standoff feature  3903  on the cap faces up. This may indicate a home position. Now the rod bender can rotate the rod to a position so that after the rod is bent completely, the standoff feature  3903  faces up when properly oriented for fixation to the patient. In this way a desired orientation of the rod may be indicated to the user (e.g., surgeon) when placing/fixing the rod to the spinal screws. 
     According to some embodiments of inventive concepts, sterility of the mechanical housing  121  (also referred to as a top assembly) may be maintained throughout rod bending operations. In particular, the mechanical housing  121  may be compatible with autoclave sterilization, and a sterile drape can be used to isolate the motor housing  122  from the sterile surgical environment while providing mechanical coupling between the mechanical and motor housings. During rod bending operations, the rod is thus in contact with components of the sterile mechanical housing  121  while the rod is isolated from the motor housing  122  which may be incompatible with autoclave sterilization. 
     According to some embodiments of inventive concepts, placement of the rod bender system on a cart may improve mobility of the system. 
     According to some embodiments of inventive concepts, an automatic springback equation calculation can be performed on a sacrificial rod (matched to the actual rod implant) to enable the rod bender to bend rods of any material without any prior data regarding the rod&#39;s material/springback properties. 
     According to some embodiments of inventive concepts, a rod bending system may be able to seamlessly capture and shape surgical rod implants based on multiple different acquisition methods. The open platform design may allow a user to select the implant system that best suits the patient. 
     According to some embodiments of inventive concepts, a rod bending system may also be able to rapidly shape the rod implant in under two minutes, reducing an amount of time the patient is under anesthesia as well as reducing stress on the patient when inserting the rod implant. 
     According to some embodiments of inventive concepts, a rod bending system may use patient specific transformation points (including live transformation points generated based on fluoroscopy) to capture attachment points. This may assist in generating a best-fit shape for the attachment/bend plan. 
       FIG. 40  is a block diagram illustrating elements of controller  102  of rod bending system  10 . As shown, controller  102  may include processor  4007  (also referred to as a processor circuit or processor circuitry) coupled with input interface  4001  (also referred to as an input interface circuit or input interface circuitry), output interface  4003  (also referred to as an output interface circuit or output interface circuitry), control interface  4005  (also referred to as a control interface circuit or control interface circuitry), and memory  4009  (also referred to as a memory circuit or memory circuitry). Memory  4009  may include computer readable program code that when executed by processor  4007  causes processor  4007  to perform operations according to embodiments disclosed herein. According to other embodiments, processor  4007  may be defined to include memory so that a separate memory circuit is not required. 
     As discussed herein, operations of controlling a rod bending system according to some embodiments of the present disclosure may be performed by controller  102  including processor  4007 , input interface  4001 , output interface  4003 , and/or control interface  4005 . For example, processor  4007  may receive user input through input interface  4001 , and such user input may include user input received through a touch sensitive portion of display  118  and/or through other user input such as a keypad(s), joystick(s), track ball(s), mouse(s), etc. Processor  4007  may also receive optical input information from camera  114  and/or feedback information from bending robot  100  through input interface  5001 . Processor  4007  may provide output through output interface  4003 , and such output may include information to render graphic/visual information on display  118 . Processor  4007  may provide robotic control information/instruction through control interface  4005  to bending robot  100 , and the robotic control instruction may be used, for example, to control operation of rod feeding subassembly  106 , brake subassembly  108 , and/or bending subassembly  110 . 
       FIG. 41  illustrates operations of controller  102  according to some embodiments of inventive concepts. 
     At block  4101 , processor  4007  may provide a set of transformation points corresponding to respective attachment implants (e.g., screws). The transformation points of the set may be provided, for example, based on at least one of: optically capturing locations of attachment implants affixed to a patient using camera  114  (e.g., using a tracked probe to point to attachment implants); locations of actual attachment implants in a medical image; and/or locations of virtual attachment implants in a medical image. 
     At block  4105 , processor  4007  may generate a bend plan for the surgical rod based on the set of transformation points. The bend plan, for example, may define a plurality of bend angles at respective bend positions along the surgical rod and corresponding rotational positions. 
     At block  4109 , processor  4007  may generate an image output (provided through output interface  4003  to display  118 ) to render the set of transformation points and the bend plan on display  118  as discussed above, for example, with respect to  FIGS. 33, 34, 35, and 36 . As shown in embodiments of  FIGS. 33, 34, 35, and 36 , the image output may be generated to render the set of transformation points and the bend plan in a first plane (e.g., the Sagittal plane) on a first portion of the display  118  and to render the set of transformation points and the bend plan in a second plane (e.g., the coronal plane) on a second portion of the display  118 , with the first and second planes being different (e.g., orthogonal). As shown in embodiments of  FIG. 35 , the image output may be generated to render the set of transformation points and the bend plan together with a medical image (e.g., a computed tomography CT scan image, an magnetic resonance imaging MRI image, and/or a fluoroscopy image) on the display  118 . As further shown in  FIG. 35 , the image output may be generated to render the set of transformation points and the bend plan on the display  118  with a medical image including real/virtual attachment implants (e.g., screws). 
     At block  4111 , processor  4007  may proceed with rod bending responsive to receiving user input (through input interface  4001 ) to proceed. For example, the user (e.g., surgeon) may adjust one or more of the transformation points on the display  118  to adjust the bend plan before actually bending the surgical rod. 
     At block  4131 , a sacrificial rod  106 ′ may be used to determine a springback characteristic for the surgical rod  106  before bending the surgical rod as discussed above, for example, with respect to  FIGS. 27 and 28 . Responsive to user input to accept/use the bend plan at block  4111 , processor  4007  may generate image output (provided through output interface  4003  to display  118 ) to render a prompt on display  118  to load sacrificial rod  106 ′ into bending robot  100 , and once the sacrificial rod has been loaded, processor  4007  may proceed with determining the springback characteristic for the surgical rod using the sacrificial rod  106 ′. Processor  4007  may proceed with springback characteristic determination responsive to determining loading of the sacrificial rod based on feedback (received through input interface  4001 ) from bending robot  100  and/or camera  118  and/or based on user input (e.g., received through a touch sensitive portion of display  118  and input interface  4001 ) that loading is complete. 
     As discussed above, the springback characteristic may be determined based on a detected springback of the sacrificial rod  106 ′ at two different bend angles. Accordingly, processor  4007  may generate instruction (provided through control interface  4005  to bending robot  100 ) to bend the sacrificial rod  106 ′ at a first test position to a first test bend angle, and responsive to this instruction, rod feeding subassembly  104  of bending robot  100  may feed the sacrificial rod  106 ′ to the first test position, brake subassembly  108  may lock the sacrificial rod  106 ′ in the first test position, and bending subassembly  110  may bend the sacrificial rod to the first test bend angle. Processor  4007  may then determine a first springback from the first test bend angle, for example, based on optical feedback received through camera  114  and/or based on detecting a point at which the bending subassembly reengages the sacrificial rod after release. Processor  4007  may then generate instruction (provided through control interface  4005  to bending robot  100 ) to bend the sacrificial rod  106 ′ at a second test position to a second test bend angle, and responsive to this instruction, rod feeding subassembly  104  of bending robot  100  may feed the sacrificial rod  106 ′ to the second test position, brake subassembly  108  may lock the sacrificial rod  106 ′ in the second test position, and bending subassembly  110  may bend the sacrificial rod  106 ′ to the second test bend angle. Processor  4007  may then determine a second springback from the second test bend angle, for example, based on optical feedback received through camera  114  and/or based on detecting a point at which the bending subassembly reengages the sacrificial rod  106 ′ after release. Processor  4007  may then determine the springback characteristic for the surgical rod based on the first springback from the first test bend angle from the sacrificial rod  106 ′ and the second springback from the second test bend angle for the sacrificial rod  106 ′. While determination of the springback characteristic is shown after generating the bend plan, the springback characteristic may be determined at any time prior to rod bending. 
     Once the springback characteristic for the surgical rod  106  has been determined, processor  4007  may generate a prompt on display  118  to load the surgical rod  106  into bending robot  100 , and once the surgical rod has been loaded, processor  4007  may proceed with bending operations of block  4135  as discussed below. Processor  4007  may proceed with bending operations responsive to determining loading of the surgical rod based on feedback (received through input interface  4001 ) from bending robot  100  and/or camera  118  and/or based on user input (e.g., received through a touch sensitive portion of display  118  and input interface  4001 ) that loading is complete. 
     At block  4135 , processor  4007  may generate instruction to bend the surgical rod based on the bend plan and based on the springback characteristic for the surgical rod in block  4131 . Accordingly, instruction for each bend may be provided so that bending subassembly  110  bends the surgical rod (based on the springback characteristic) past the desired bend angle so that that the desired bend angle is achieved after springback. Rod bending operations of block  4135  are illustrated in greater detail in  FIG. 44 . 
     At block  4401 , processor  4007  may generate instruction (provided through control interface  4005  to bending robot  100 ) to feed the surgical rod to a first bend position of the plurality of bend positions. Responsive to this instruction, rod feeding subassembly  104  may feed the surgical rod to the first bend position. 
     At block  4405 , processor  4007  may generate instruction (provided through control interface  4005  to bending robot  100 ) to rotate the surgical rod to a first rotational position. Responsive to this instruction, rod feeding subassembly  104  may rotate the surgical rod to the first rotational position. 
     At block  4409 , processor  4007  may generate instruction (provided through control interface  4005  to bending robot  100 ) to bend the surgical rod to a first bend angle of the plurality of bend angles while the surgical rod is maintained at the first bend position and the first rotational position. Responsive to this instruction, brake subassembly  108  may lock the surgical rod in the first bend position and the first rotational position while bending subassembly  110  bends the surgical rod to the first bend angle (e.g., bending the surgical rod past the first bend angle in accordance with the springback characteristic so that the first bend angle is achieved after completion of the operation). 
     At block  4411 , processor  4007  may generate ( 4401 ) instruction (provided through control interface  4005  to bending robot  100 ) to feed the surgical rod to a next bend position of the plurality of bend positions. Responsive to this instruction, rod feeding subassembly  104  may feed the surgical rod to the next bend position. 
     At block  4415 , processor  4007  may generate instruction (provided through control interface  4005  to bending robot  100 ) to rotate the surgical rod to a next rotational position. Responsive to this instruction, rod feeding subassembly  104  may rotate the surgical rod to the next rotational position. 
     At block  4419 , processor  4007  may generate instruction (provided through control interface  4005  to bending robot  100 ) to bend the surgical rod to a next bend angle of the plurality of bend angles while the surgical rod is maintained at the next bend position and the next rotational position. Responsive to this instruction, brake subassembly  108  may lock the surgical rod in the next bend position and the next rotational position while bending subassembly  110  bends the surgical rod to the next bend angle (e.g., bending the surgical rod past the next bend angle in accordance with the springback characteristic so that the next bend angle is achieved after completion of the operation). 
     Operations of blocks  4411 ,  4415 , and  4419  may be repeated for each bend of the bend plan provided to fit the surgical rod to the attachment implants (e.g., screws) corresponding to the transformation points, until rod bending is complete at block  4421 . 
     According to some embodiments, operations  4431 ,  4435 , and  4439  may be performed to provide a final bend (also referred to as an extra bend) configured to provide a stop with respect to an attachment implant (e.g., screw) corresponding to the last of the transformation points. Such bends are discussed above with respect to  FIG. 37 . 
     At block  4431 , processor  4007  may generate instruction (provided through control interface  4005  to bending robot  100 ) to feed the surgical rod to a final bend position after the last of the transformation points for the bend plan. Responsive to this instruction, rod feeding subassembly  104  may feed the surgical rod to the final bend position. 
     At block  4435 , processor  4007  may generate instruction (provided through control interface  4005  to bending robot  100 ) to rotate the surgical rod to a final rotational position. Responsive to this instruction, rod feeding subassembly  104  may rotate the surgical rod to the final rotational position. 
     At block  4439 , processor  4007  may generate instruction (provided through control interface  4005  to bending robot  100 ) to bend the surgical rod to the final bend angle while the surgical rod is maintained at the final bend position and the final rotational position. Responsive to this instruction, brake subassembly  108  may lock the surgical rod in the final bend position and the final rotational position while bending subassembly  110  bends the surgical rod to the final bend angle. As noted above, the final bend angle may be configured to provide a stop with respect to the attachment implant corresponding to the last of the transformation points. 
     According to some embodiments, instructions from different blocks of  FIG. 44  may be provided separately to bending robot  100  as each operation is performed, or instructions from different blocks of  FIG. 44  may be provided to bending robot  100  together so that bending robot may perform instructions from a group of blocks with some autonomy. According to some embodiments, controller  102  may be defined to include control elements at bending robot  100 , and according to some other embodiments, bending robot  100  may include a separate controller that received instruction from controller  102  to control bending operations at bending robot  100  based on instruction from controller  102 . 
     At block  4139  of  FIG. 41 , processor  4007  may verify a shape of the surgical rod based on the bend plan and based on optical feedback received through camera  114  after completion of bending the surgical rod at each of the bend positions. For example, the optical feedback may be used to identify a location of at least one point of the rod in space based on a position of a probe tracked using camera  118 . Such verification may be performed, for example, as discussed above with respect to implant shaping verification (e.g., tip verification, shape verification, tool verification, etc.). Processor  4007 , for example, may determine a numerical verification score that is provided on display  118 , and/or may provide a pass/fail indication on display  118 . 
     At block  4141 , processor  4007  may generate instruction (provided through control interface  4005  to bending robot  100 ) to cut the surgical rod after completion of bending the surgical rod at each of the bend positions. Responsive to this instruction, bending robot  100  may cut the surgical rod to remove excess portions there so that the surgical rod can be secured to the attachment implants (screws). While instruction to cut the surgical rod may follow instruction to verify rod shape according to some embodiments, according to some other embodiments, the order may be reversed. 
       FIG. 42  illustrates operations of controller  102  according to some other embodiments of inventive concepts. 
     At block  4201 , processor  4007  may provide an initial set of transformation points corresponding to respective attachment implants (e.g., screws). The transformation points of the initial set may be provided, for example, based on at least one of: optically capturing locations of attachment implants affixed to a patient using camera  114  (e.g., using a tracked probe to point to attachment implants); locations of actual attachment implants in a medical image; and/or locations of virtual attachment implants in a medical image. 
     At block  4205 , processor  4007  may generate an initial bend plan for the surgical rod based on the initial set of transformation points. The initial bend plan, for example, may define a plurality of bend angles at respective bend positions along the surgical rod and corresponding rotational positions. 
     At block  4209 , processor  4007  may generate an initial image output (provided through output interface  4003  to display  118 ) to render the initial set of transformation points and the initial bend plan on display  118 , as discussed above, for example, with respect to  FIGS. 33, 34, and 35 . As shown in embodiments of  FIGS. 33, 34, and 35 , the initial image output may be generated to render the initial set of initial transformation points and the initial bend plan in a first plane (e.g., the Sagittal plane) on a first portion of the display  118  and to render the initial set of transformation points and the initial bend plan in a second plane (e.g., the coronal plane) on a second portion of the display  118 , with the first and second planes being different (e.g., orthogonal). As shown in embodiments of  FIG. 35 , the initial image output may be generated to render the initial set of transformation points and the initial bend plan together with a medical image (e.g., a computed tomography CT scan image, an magnetic resonance imaging MRI image, and/or a fluoroscopy image) on the display  118 . As further shown in  FIG. 35 , the initial image output may be generated to render the initial set of transformation points and the bend plan on the display  118  with a medical image including real/virtual attachment implants (e.g., screws). 
     After providing the initial image output on display  118 , processor  4007  may accept user input to adjust one or more transformation points of the initial set as discussed below. At blocks  4211  and  4215 , processor  4007  may accept user input to adjust one of the transformation points. As discussed above with respect to  FIGS. 33, 34, and 35 , for example, one of the transformation points (e.g., transformation point S1, as shown) may be selected (e.g., via touch sensitive portions of display  118  or other user input) and moved/dragged (e.g., via touch sensitive portions of display  118  or other user input). Responsive to user input to adjust the transformation point (e.g., transformation point S1, as shown), processor  4007  may adjust the transformation point to provide an adjusted set of transformation points at block  4219 . 
     At block  4221 , processor  4007  may generate an adjusted bend plan for the surgical rod based on the adjusted set of transformation points. The adjusted bend plan may thus define an adjusted plurality of bend angles at respective adjusted bend positions along the surgical rod and corresponding adjusted rotational positions determined based on the adjusted transformation point. 
     At block  4225 , processor  4007  may generate an adjusted image output (provided through output interface  4003  to display  118 ) to render the adjusted set transformation points and the adjusted bend plan on display  118 . the adjusted image output may be generated to render the adjusted set of transformation points and the adjusted bend plan in a first plane (e.g., the Sagittal plane) on a first portion of the display  118  and to render the adjusted set of transformation points and the adjusted bend plan in a second plane (e.g., the coronal plane) on a second portion of the display  118 , with the first and second planes being different (e.g., orthogonal). Moreover, the adjusted image output may be generated to render the adjusted set of transformation points and the adjusted bend plan together with a medical image (e.g., a computed tomography CT scan image, an magnetic resonance imaging MRI image, and/or a fluoroscopy image) on the display  118 . In addition, the adjusted image output may be generated to render the adjusted set of transformation points and the adjusted bend plan on the display  118  with a medical image including real/virtual attachment implants (e.g., screws). 
     Operations of blocks  4211 ,  4215 ,  4219 ,  4221 ,  4225 , and  4229  may be repeated any number of times to adjust any number of the transformation points any number of times until user input is received (e.g., through a touch sensitive portion of display  118  or other user input device) to accept the bend plan at block  4229 . If no user input is provided at block  4221 , the initial bend plan may be accepted at block  4229  to provide an accepted bend plan. If one or more transformation points are adjusted at blocks  4211 ,  4215 ,  4219 , one or more adjusted bend plans may be generated at block  4221 , and the final adjusted bend plan may become the accepted bend plan. The resulting accepted bend plan may then be used to proceed with operations of blocks  4131 ,  4135 ,  4139 , and/or  4141 , which may be performed as discussed above with respect to  FIG. 41 . 
       FIG. 43  illustrates operations of controller  102  according to still other embodiments of inventive concepts. 
     At block  4301 , processor  4007  may provide a first set of transformation points corresponding to respective attachment implants. The transformation points of the first set may be provided, for example, based on at least one of: optically capturing locations of attachment implants affixed to a patient using camera  114  (e.g., using a tracked probe to point to attachment implants); locations of actual attachment implants in a medical image; and/or locations of virtual attachment implants in a medical image. 
     At block  4305 , processor  4007  may generate a first bend plan for the surgical rod based on the first set of transformation points. The first bend plan, for example, may define a first plurality of bend angles at respective bend positions along the surgical rod and corresponding rotational positions. 
     At block  4309 , processor  4007  may provide a second set of transformation points corresponding to the respective attachment implants, with the first and second sets of transformation points being different. The transformation points of the second set may be provided, for example, based on at least one of: optically capturing locations of attachment implants affixed to a patient using camera  114  (e.g., using a tracked probe to point to attachment implants); locations of actual attachment implants in a medical image; and/or locations of virtual attachment implants in a medical image. For example, the first set of transformation points may be provided based on preoperative medical imaging with virtual attachment implants (e.g., screws) placed therein, and the second set of transformation points may be provided based on intra-operative medical imaging after fixation of real/actual attachment implants (e.g., screws). 
     At block  4311 , processor  4007  may generate a second bend plan for the surgical rod based on the second set of transformation points, with the first and second bend plans being different. The second bend plan, for example, may define a second plurality of bend angles at respective bend positions along the surgical rod and corresponding rotational positions. 
     At block  4315 , processor  4007  may generate a third bend plan for the surgical rod based on merging the first and second bend plans and/or based on merging the first and second sets of transformation points as discussed above, for example, with respect to  FIG. 36 . In addition, processor  4007  may generate a third set of transformation points based on merging the first and second sets of transformation points. Processor  4007 , for example, may generate the transformation points of the third set based on averaging/merging respective transformation points of the first and second sets and/or based on determining midpoints between respective transformation points of the first and second sets. Processor  4007  may then generate the third bend plan based on the third set of transformation points. The third bend plan (also referred to as a merged bend plan) may thus define a plurality of bend angles at respective bend positions along the surgical rod and corresponding rotational positions. 
     At block  4325 , processor  4007  generate an image output (provided through output interface  4003  to display  118 ) to render the first, second, and third bend plans on display  118  as discussed above, for example, with respect to  FIG. 36 . 
     As shown in embodiments of  FIG. 36 , the image output may be generated to render the first, second, and third sets of transformation points and the respective first, second, and third bend plans in a first plane (e.g., the Sagittal plane) on a first portion of the display  118  and to render the first, second, and third sets of transformation points and the respective first, second, and third bend plans in a second plane (e.g., the coronal plane) on a second portion of the display  118 , with the first and second planes being different (e.g., orthogonal). In addition, the image output may be generated to render the sets of transformation points and the bend plans together with a medical image (e.g., a computed tomography CT scan image, an magnetic resonance imaging MRI image, and/or a fluoroscopy image) on the display  118 . Moreover, the image output may be generated to render the sets of transformation points and the bend plans on the display  118  with a medical image including real/virtual attachment implants (e.g., screws). 
     At block  4319 , processor  4007  may wait for user acceptance of the third bend plan before proceeding with operations of blocks  4131 ,  4135 ,  4139 , and/or  4141 . For example, processor  4007  may wait until user input is received (e.g., through a touch sensitive portion of display  118  or other user input device) to accept the third bend plan at block  4329 . While not explicitly shown in  FIG. 43 , operations similar to those of  FIG. 42  may allow the user to adjust one or more of the first, second, and/or third sets of transformation points that are used to generate the respective bend plans before accepting the third bend plan. The resulting accepted bend plan may then be used to proceed with operations of blocks  4131 ,  4135 ,  4139 , and/or  4141 , which may be performed as discussed above with respect to  FIG. 41 . 
     In the above-description of various embodiments of present inventive concepts, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of present inventive concepts. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which present inventive concepts belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     When an element is referred to as being “connected”, “coupled”, “responsive”, or variants thereof to another element, it can be directly connected, coupled, or responsive to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected”, “directly coupled”, “directly responsive”, or variants thereof to another element, there are no intervening elements present. Like numbers refer to like elements throughout. Furthermore, “coupled”, “connected”, “responsive”, or variants thereof as used herein may include wirelessly coupled, connected, or responsive. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Well-known functions or constructions may not be described in detail for brevity and/or clarity. The term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be understood that although the terms first, second, third, etc. may be used herein to describe various elements/operations, these elements/operations should not be limited by these terms. These terms are only used to distinguish one element/operation from another element/operation. Thus a first element/operation in some embodiments could be termed a second element/operation in other embodiments without departing from the teachings of present inventive concepts. The same reference numerals or the same reference designators denote the same or similar elements throughout the specification. 
     As used herein, the terms “comprise”, “comprising”, “comprises”, “include”, “including”, “includes”, “have”, “has”, “having”, or variants thereof are open-ended, and include one or more stated features, integers, elements, steps, operations, components, functions or groups but do not preclude the presence or addition of one or more other features, integers, elements, steps, operations, components, functions or groups thereof. Furthermore, as used herein, the common abbreviation “e.g.”, which derives from the Latin phrase “exempli gratia,” may be used to introduce or specify a general example or examples of a previously mentioned item, and is not intended to be limiting of such item. The common abbreviation “i.e.”, which derives from the Latin phrase “id est,” may be used to specify a particular item from a more general recitation. 
     Example embodiments are described herein with reference to block diagrams and/or flowchart illustrations of computer-implemented methods, apparatus (systems and/or devices) and/or computer program products. It is understood that a block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by computer program instructions that are performed by one or more computer circuits. These computer program instructions may be provided to a processor circuit (also referred to as a processor) of a general purpose computer circuit, special purpose computer circuit, and/or other programmable data processing circuit to produce a machine, such that the instructions, which execute via the processor of the computer and/or other programmable data processing apparatus, transform and control transistors, values stored in memory locations, and other hardware components within such circuitry to implement the functions/acts specified in the block diagrams and/or flowchart block or blocks, and thereby create means (functionality) and/or structure to implement the functions/acts/operations specified in the block diagrams and/or flowchart block(s). 
     These computer program instructions may also be stored in a tangible computer-readable medium that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of manufacture including instructions which implement the functions/acts specified in the block diagrams and/or flowchart block or blocks. Accordingly, embodiments of present inventive concepts may be embodied in hardware and/or in software (including firmware, resident software, micro-code, etc.) that runs on a processor such as a digital signal processor, which may collectively be referred to as “circuitry,” “a module” or variants thereof. 
     It should also be noted that in some alternate implementations, the functions/acts noted in the blocks may occur out of the order noted in the flowcharts. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending upon the functionality/acts involved. Moreover, the functionality of a given block of the flowcharts and/or block diagrams may be separated into multiple blocks and/or the functionality of two or more blocks of the flowcharts and/or block diagrams may be at least partially integrated. Finally, other blocks may be added/inserted between the blocks that are illustrated, and/or blocks/operations may be omitted without departing from the scope of inventive concepts. Moreover, although some of the diagrams include arrows on communication paths to show a primary direction of communication, it is to be understood that communication may occur in the opposite direction to the depicted arrows. 
     Although several embodiments of inventive concepts have been disclosed in the foregoing specification, it is understood that many modifications and other embodiments of inventive concepts will come to mind to which inventive concepts pertain, having the benefit of teachings presented in the foregoing description and associated drawings. It is thus understood that inventive concepts are not limited to the specific embodiments disclosed hereinabove, and that many modifications and other embodiments are intended to be included within the scope of the appended claims. It is further envisioned that features from one embodiment may be combined or used with the features from a different embodiment(s) described herein. Moreover, although specific terms are employed herein, as well as in the claims which follow, they are used only in a generic and descriptive sense, and not for the purposes of limiting the described inventive concepts, nor the claims which follow. The entire disclosure of each patent and patent publication cited herein is incorporated by reference herein in its entirety, as if each such patent or publication were individually incorporated by reference herein. Various features and/or potential advantages of inventive concepts are set forth in the following claims.