Navigated articulating interbody device and surgical navigation system

Abstract

A system for delivering an implant to a surgical site under surgical navigation guidance includes an instrument that is configured to deliver the implant to the surgical site. The implant is detachably coupled to the instrument, wherein the instrument is configured to controllably articulate the implant relative to the instrument. The system further includes a mechanism that allows the relative position of the implant relative to the instrument to be determined and conveyed to a user of the system. The instrument has a first trackable element which is configured to be detectable by a surgical navigation guidance system for allowing real-time tracking of the instrument.

Description

[0001] NAVIGATED ARTICULATING INTERBODY DEVICE AND SURGICAL NAVIGATION SYSTEM

[0002] Cross-Reference to Related Application

[0003] The present application claims priority to and the benefit of US patent application serial No. 63 / 749,328, filed January 24, 2025, which is hereby incorporated by reference in its entirety.

[0004] Technical Field

[0005] The present application relates to navigation of surgical instruments and more particularly, to a navigated articulating interbody and system and method for using surgical navigation to deliver an implant, such as a transforaminal lumbar interbody fusion implant.

[0006] Background

[0007] Navigation systems are commonly used in many types of surgical procedures. A surgical navigation system, much like a commonly used navigation system in a car, attempts to localize or determine a position in space in the context of its surroundings, in this case the operating room in which the surgery is performed. The actual localization technology, however, differs since surgical navigation is not using triangulation like a global positioning system with the help of several geostationary satellites. Modern surgical navigation systems use a stereoscopic camera emitting infrared light which can determine a 3D position of prominent structures, like reflective marker spheres. This allows for real-time tracking of the marker spheres.

[0008] A basic setup for such a system includes a stereoscopic camera, a computer platform with screen, and the respective navigation software. During the surgery, the marker spheres are attached to the patient and at surgical instruments (using reference arrays) to enable an exact localization in space and hence navigation in the operating room (OR). With each reference array comprising at least three marker spheres, the computer can calculate the position and orientation of each instrument. A correct localization and virtual display of the instrument on the computer screen is ensured by firmly attaching a reference array to the patient, e.g., in the bone or via a head clamp. Movements of the camera intraoperatively are possible because only the relative position of the tracked instruments to the tracked patient reference is relevant.Stereotactic navigation allows for real-time 3-D tracking of surgical instruments, and is becoming the standard of care for spinal instrumentation and pedicle screw' placement during spine surgery. Nearly all major “pedicle screw” systems are compatible with navigation.

[0009] One type of spinal surgery is transforaminal lumbar interbody fusion (TLIF), which is a spinal fusion technique for the lower back, in which two spinal bones (vertebrae) are joined by removing a portion of the spinal disc between them and placing a spacer (cage), supplemented by screws and rods, in its place. Removing the disc and fusing the vertebrae eliminates motion in that spinal segment (meaning two vertebrae and the intervertebral disc) and reduces back pain. Placing a spacer reduces compression on the nerves by giving them more room. This alleviates sciatica back and leg pain.

[0010] Stereotactic navigation has recently been introduced for TLIF (transforaminal lumbar interbody fusion) implants, which are cages that replace the disc between the vertebral bodies. TLIF is the most popular approach for interbody cages. The procedure utilizes a transforaminal lumbar interbody fusion (TLIF) inserter which is a specialized surgical tool used to place a bone graft or cage into the disc space between vertebrae during a TLIF spinal fusion. In the case of a TILF procedure, navigation typically works by tracking the handle or TILF inserter using several optical tracking spheres that are tracked by a camera to locate their exact position in space. The position of the inserter in turn allows a degree of tracking of the implant or instrument which is rigidly attached to inserter.

[0011] There are two types of TLIF spacers / cages: traditional “bullet” cages (Fig. 2B), with a bullet shape, and “banana” or “crescent” cages with a curved shape (Fig. 2 A). Multiple recent studies have shown that banana cages are biomechanically superior as they can be placed on die anterior apophyseal ring at die front of die vertebral body. It will be appreciated that the TLIF cage is broadly an implant for implantation at the surgical site and thus, the terms “spacer,” “cage” and “implant” can be used interchangeably. Bullet cages are inserted straight into the disc space, and thus are rigidtiy attached to the inserter, and can be easily navigated. Banana cages are placed with an “articulating” inserter, which has a hinge that allows the cage to rotate into the appropriate position. Due to the articulating nature of the insertion technique, banana cages are technically more challenging to insert. The inserter is dius die instrument by which the cage is delivered and properly positioned and oriented at the surgical site.

[0012] There at least two challenges associated with the use of banana / crescent TLIF cage, namely: 1) insertion of a banana / crescent TLIF cage is technically more challenging, as thesurgeon needs to rotate a cage in an area that is not under direct visualization and therefore, this procedure would benefit greatly from stereotactic navigation; and 2) banana / crescent TLIF cages are difficult to “navigate” as the navigation traditionally tracks the instrument handle. Because the banana / crescent cages must articulate with the inserter, there is no currently known method to navigate this implant because there is no known way to track the position of an implant after it articulates at the surgical site. The disclosed devices address and provide a solution to the above challenges.

[0013] Summary

[0014] A system for delivering an implant to a surgical site under surgical navigation guidance includes an instrument that is configured to deliver the implant to the surgical site. The implant is detachably coupled to the instrument, wherein the instrument is configured to controllably articulate the implant relative to the instrument. The system further includes a mechanism that allows the relative position of the implant relative to the instrument to be determined and conveyed to a user of the system. The instrument has a first trackable element which is configured to be detectable by a surgical navigation guidance system for allowing real-time tracking of the instrument.

[0015] A computer-implemented method, comprises the steps of:

[0016] obtaining, at a processor, first data for an image of a surgical environment; determining, at the processor, a position of a surgical instrument;

[0017] displaying, at a display device, the image of the surgical environment and overlaying a graphical representation of the surgical instrument at the determined position of the surgical instrument, said graphical representation comprising a representation of an implant detachably coupled to the surgical instrument in a first position relative to the surgical instrument;

[0018] determining, at the processor, a changed angle of articulation of the implant relative to the surgical instrument; and

[0019] updating, at the display device, at least the representation of the implant to a second position to indicate the changed angle of articulation.

[0020] Brief Description of the Drawing Figures

[0021] Fig. 1 is a cross-sectional view showing one step of a TLIF procedure in which damaged portions of a disc are removed and prepared for insertion of an implant in the form of a spacer (cage);Fig. 2A is a cross-sectional view of a prepared disc with a spacer according to a first embodiment implanted (inserted) therein;

[0022] Fig. 2B is a cross-sectional view of a prepared disc with a spacer according to a first embodiment implanted (inserted) therein;

[0023] Fig. 2C is a perspective view of one exemplary spacer;

[0024] Fig. 3 is a perspective view of an operating room with a surgical navigation system; Fig. 4A illustrates a first step of inserting the spacer into the prepared disc site; Fig. 4B illustrates a second step in which the spacer is articulated to a first articulated position within the prepared disc site;

[0025] Fig. 4C illustrates a third step in which the spacer is articulated to a second articulated position within the prepared disc site;

[0026] Fig. 4D illustrates a fourth step in which the spacer is articulated to a third articulated position within the prepared disc site;

[0027] Fig. 5 is a first cross-sectional view of an articulating inserter having an implant (spacer) coupled thereto and illustrating a first articulation mechanism;

[0028] Fig. 6 is a second cross-sectional view of the articulating inserter of Fig. 5;

[0029] Fig. 7 A is an exploded side elevation view of an articulating inserter illustrating a second implant articulation mechanism and showing the implant (spacer) exploded therefrom;

[0030] Fig. 7B is an exploded side elevation view of the articulating inserter of Fig. 7A with the implant (spacer) coupled thereto;

[0031] Fig. 7C is a side elevation view, with break-away lines

[0032] indicating indeterminate length, showing the implant (spacer) coupled to a third implant articulation mechanism;

[0033] Fig. 7D is a side elevation view showing a first movement of the third implant articulation mechanism which is translated into a first articulation movement of the implant;

[0034] Fig. 7E is a side elevation view showing a second movement of die third implant articulation mechanism which is translated into a second articulation movement of the implant;

[0035] Fig. 8A is a cross-sectional view showing a first position indicator mechanism for detecting a position of the spacer relative to the shaft of the inserter, with the spacer being shown in a first position;

[0036] Fig. 8B is a cross-sectional view of the position indicator mechanism with the spacer being shown in a second position;Fig. 9 shows another mechanism for detecting a position of the spacer relative to the shaft (i.e., the angle of articulation);

[0037] Fig. 10 is an exploded perspective view of an inserter with spacer illustrating a first mechanism for determing an angle of articulation of the spacer relative to the inserter;

[0038] Fig. 11 is a perspective view of an inserter with spacer illustrating a second mechanism for determing an angle of articulation of the spacer relative to the inserter;

[0039] Fig. 12 is a perspective view of an inserter with spacer illustrating a third mechanism for determing an angle of articulation of the spacer relative to the inserter;

[0040] Fig. 13 A is a view of a display that shows a preoperative image of the sugicai site, in this case an image of the vertebrae; and

[0041] Fig. 13B is a view of the display that shows the preoperative image of the sugicai site with superimposed images of the surgical instrument and the implant; and

[0042] Fig. 14 is a flow diagram of a process of displaying the inserter and updating the display of the spacer in accordance with one or more exemplary implementations of the present disclosure..

[0043] Detailed Description of Certain Embodiments

[0044] As discussed herein, surgical operating rooms traditionally contain a diverse range of medical equipment, which can include computer assisted surgical navigation systems, medical imaging devices (e.g., computerized tomography (CT) scanners, fluoroscopy imaging, etc.), surgical robots, etc.

[0045] A computer assisted surgical navigation system provides a surgeon with computerized visualization of the present pose of a surgical tool relative to medical images of a patient's anatomy. Camera tracking systems for computer assisted surgical navigation typically use a set of cameras to track pose of a reference array on a surgical tool, which is being positioned by a surgeon during surgery, relative to a patient reference array attached to a patient. The reference arrays allow the camera tracking system to determine a pose of the surgical tool relative to anatomical structure imaged by a medical image of the patient and relative to the patient. The surgeon can thereby use real-time visual feedback of the position to navigate the surgical tool during a surgical procedure on the patient.

[0046] Many surgical workflows using computer assisted surgical navigation systems require image scans, such as CT scans or magnetic resonance imaging scans, during

[0047] the surgical procedure. Perpendicular scan slices (axial, sagittal, and coronal) are often usedto enable a surgeon to visualize the patient's anatomy alongside the relative poses of surgical instruments that are shown on the display.

[0048] Navigation assisted spine surgery is a group of technologies, which allow the surgeon to access real-time, three dimensional and virtual images of the spine in relation to the surgical instruments intraoperatively. There are numerous commercially available surgical navigation systems that are suitable for use with the surgical instruments described herein and are suitable for use in a TLIF procedure. Fig. 3 illustrates the basic components of a surgical navigation system 10.

[0049] The basic fundamentals of the exemplary surgical navigation system 10 include the following:

[0050] Image Acquisition and Processing Unit

[0051] The first step in spinal navigation is to acquire high-resolution images of the region of interest, either preoperatively or intraoperatively, which then allows the surgeon to navigate upon these processed images. Intraoperative imaging can be done either by fluoroscopy, computerized tomography (CT) scan and even magnetic resonance imaging (MRI).

[0052] For example, planning for surgery can be based on CT images obtained preoperatively. Planning can be also done using medical images obtained from different devices (MRI, fluoroscopy, scanners, etc.). The CT images must have proper resolution which can be achieved using standard scanners. The surgeon using standard surgical views (Axial, Sagittal, Coronal) and a 3D view defines natural landmarks and generates 3D model of the vertebrae. Data is saved to the file which can be read by the navigation software described herein. Fig. 13A shows a 3D model 600 of the spine which represents the target surgical site.

[0053] With reference to Fig. 3, the surgical navigation system 10 includes a computer workstation (or computing device) 20 suitable for executing navigation software. The computer workstation 20 includes a memory 25, a user interface 27, and a central processing unit (“CPU”) 29 for executing the navigation software, for example, stored on memory 25, that processes imaging data and calculates instrument positions in real time. The system 10 also includes one or more high-resolution displays 30 that display 2D and 3D images of the patient's anatomy and the navigated instruments. One of the other major components of the surgical navigation system 10 is a referencing system that can include a dynamic reference frame / array (DRA) 50, light emitting diodes (LED) / reflective markers 60 and a tracking system.

[0054] The dynamic reference array (DRA) 50 is usually attached to fixed anatomical landmarks, which differ depending upon the surgical procedure. The preoperative image istaken along with the fixed DRA 50, which serves to synchronize between the virtual navigated images and anatomical landmarks. The accuracy of the navigation depends on the stable fixation of this DRA 50, and, therefore, it must be left undisturbed throughout the surgery.

[0055] The DRA 50 typically has provisions for attaching three or more spheres known as light-emitting diodes (LED) 60 in one embodiment. These LEDs 60 emit light, which is tracked by an electro-optical camera 75 and are known as active arrays. Specialized surgical instruments are used, which also have LEDs 60 attached to them and are called passive arrays as they reflect the infrared rays emitted from the camera and gives the surgeon a real-time tracking of the exact location of these devices over the surgical field. The 3D orientation between these active and passive LEDs, thus facilitates navigation.

[0056] Various tracking systems are available that include optical, mechanical, acoustic or electromagnetic systems. Optical tracking systems are the most frequently used due to superiority in terms of accuracy. They use infrared camera devices 75 to actively track the light emitted or reflected from the LEDs / markers (spheres) 60, which are attached to the DRA 50 and the surgical instrument 100. In Fig. 5, the LEDs / markers (spheres) 60 are attached to the surgical instrument 100 via a reference body that can be clamped to the shaft of surgical instrument 100.

[0057] They calculate the location and provide real-time three-dimensional positional data of the handheld surgical instruments in relation to the surgical field. This requires the “line of sight” maintenance between the LEDs / markers 60 and cameras 75 at all times. Hand movements or excess operating personnel across this line of sight might hinder the navigation process. Electromagnetic systems allow an unobstructed view between transmitter and receiver. However, significant interference of the images can occur due to metal artifacts and electromagnetic fields originating from other commonly used operating room devices such as cautery and electrocardiogram monitoring equipment.

[0058] The navigation software uses "transformation matrices" to convert the tracked tool's physical coordinates into the digital coordinates of the 3D anatomical model. The final output is displayed on a high -definition monitor, showing a virtual representation of the instrument superimposed onto the patient's anatomical images in real-time. This allows the surgeon to see exactly, in real-time, where the tool tip is located relative to hidden internal structures.

[0059] Accordingly, Fig. 3 depicts the surgical navigation system 10 includes the camera device 75 that floods the surgical area with infrared light. Reflective spheres (markers) (oftenpassive, reflective balls) 60 are attached to a rigid frame (a dynamic reference frame 50 or DRF) that is firmly fixed to the patient (e.g., to the skull or spine) and also to the surgical instrument 100. These markers 60 reflect the IR light back to sensors in the camera unit 75, which can also be referred to as being a tracking unit. This type of surgical navigation system includes stereoscopic triangulation to track the objects. Because the system uses two cameras, it can triangulate the precise 3D coordinates (x, y, z) of each marker by determining the intersecting lines of sight from both cameras. The surgical navigation system utilizes a position and orientation calculation. By tracking the positions of at least three markers on a reference array, the computer calculates the exact spatial orientation (position and rotation) of the patient's anatomy and instrument(s). Real-Time Tracking: This data is continuously updated, allowing the software to display the instruments' real-time positions and movements on a screen, overlaid onto pre-operative images (like CT scans) or onto 3D computer generated models based on the pre-operative images. This type of system is described in further detail below and is shown in Fig. 3.

[0060] Thus, when attached to surgical instruments, these passive marker spheres 60 act as location points for the instruments in the OR. A tracking unit 75 floods the surgical site with infrared light. The marker spheres 60 reflect the light back to sensors on the tracking unit, determining the position and location of the surgical instrument. A fixed reference frame 50 represents the patient’s physical position. The movement of the surgical instrument 100 is compared to the patient reference frame 50 and displayed relative to the patient image set, assisting the surgeon in navigating the instrument to the target treatment site.

[0061] The image acquisition and processing unit (part of the surgical navigation system 10) further incorporates a coordinated set of hardware components that operate together to acquire, process, and visually present positional information of the articulation inserter (surgical tool / instrument) 100. In one illustrated embodiment, the navigation system 10 houses both a transmitter configured to emit IR light toward the reference array (DRF) 50 and toward the reference array on the surgical instrument 100 and a receiver for detecting the reflected signals and associated position data returned from the reference array (DRF) and from the implant. The navigation system 10 internally routes the incoming positional information to CPU 29, which contains code executing in its processor. The CPU 29 executes navigation algorithms (e.g., software stored on memory 25) that translate raw spatial data into a digitally reconstructed model of the surgical environment. As the tracking camera 75 captures the real-time pose of the surgical instrument 100 via the reference array DRF 50 and, the system continuously updates the corresponding position data, allowing thenavigation system 10 to generate a precise representation of the orientation and alignment of the tracked components.

[0062] The HD display 30 is operably connected to the navigation system 10 and presents graphical information derived from the CPU in a format suitable for direct intraoperative interpretation by the surgeon. In the present application, this includes a spine graphic that represents a patient anatomy, onto which superimposed graphic data is layered to show the virtualized depiction of the surgical instrument 100 in real time. The HD display 30 thus serves as the surgeon’s primary visualization interface, allowing the surgeon to monitor the dynamic interaction between the tracked surgical instrument 100 and the anatomical structures being navigated. Through continuous updates generated by the CPU and transmitted from the navigation system 10, the HD display 30 provides an accurate, stable, and latency-minimal representation of the operati ve field.

[0063] The tracking camera detects the spatial orientation of the reference array affixed to the inserter tool 100 or other tracked instruments. The camera 75 receives the transmitted signals emitted from the navigation system 10 and captures the reflected infrared or optical markers on the reference array to generate precise three-dimensional spatial coordinates. These coordinates make up the position data, which is conveyed back to the navigation system 10 for interpretation. The tracking camera 75 is positioned relative to the operating table 11 such that it maintains clear line-of-sight to the reference array throughout the procedure, ensuring uninterrupted tracking of die distal insertion pathway and inserter 100.

[0064] TLIF Procedure

[0065] As previously mentioned, transforaminal lumbar interbody fusion (TLIF) is a spinal fusion technique for the lower back, in which two spinal bones (vertebrae) are joined by removing a portion of the spinal disc between them and placing a spacer (cage), supplemented by screws and rods, in its place. Removing the disc and fusing the vertebrae eliminates motion in that spinal segment (meaning two vertebrae and the intervertebral disc) and reduces back pain. Placing a spacer reduces compression on the nerves by giving them more room.

[0066] After anesthesia is administered to the patient, a small incision is made in the back of the patient. To create access to the surgical site, muscles are gently moved aside (retracted) rather than cut. As shown in Fig. 1, the damaged disc 2 is removed, and the space 3 is prepared. Not all of the damaged disc 2 is removed but rather, typically around 20% to 70% of the damaged disc 2 is removed. In Fig. 1, it is seen that the peripheral portions of the disc 2 remain with a center portion removed to receive an implant in the form of a spacer (cage)90. Nerve roots are also typically moved aside to relieve pressure. After implantation of the spacer 90, screws and rods (not shown) are placed to hold the vertebrae in position. The bone graft encourages new bone to grow, permanently joining the vertebrae.

[0067] Spacer 90

[0068] The spacer (cage) is filled with bone graft material and is inserted into the disc space to restore height and provide a scaffold for fusion. As mentioned previously, there are two main types of TLIF cages; namely, a traditional “bullet” cage 89 that is shown in Fig. 2B, with a bullet shape, and a “banana” or “crescent” cage 90 with a curved shape that is shown in Fig. 2A. For purpose of the present application, the remaining figures will focus on the spacer having the bannana or crescent cage shape.

[0069] As shown in Fig. 2C, the spacer 90 has a curved (bannana or crescent) shaped body 91 with a first end and an opposing second end. The body 91 has an open internal structure 94, such as an open honeycomb structure for receiving the bone graft material. The first end represents an articulation end of the spacer 90. At the first end, which can be thought of as being a head 92, there is an articulation pivot post 95, which can be in the form of a threaded titanium insert. A threaded opening 96 is shown in Fig. 2C.

[0070] The head 92 is generally round or arcuate in shape with a bore 93 provided in the head 92 that extends from the upper surface to the lower surface and is sized to receive the post 95. The post 95 is rotatable in the bore 93 and thus relative to the spacer 90.

[0071] The spacer 90 is rotatable relative to the post 95 when the post 95 is retained relative to the spacer 90.

[0072] Surgical Instrument

[0073] To deliver and position the spacer 90 within the prepared disc 2, an articulating insert 100 is used. The articulating insert 100 is an elongated surgical instrument that has a shaft 110 having a proximal end 112 and an opposite distal end 114. As mentioned, the articulating insert 100 is the means by which the spacer (cage) 90 is delivered to the site and is able to move relative to the articulating insert 100. The spacer 90 is often connected to the inserter shaft via a central pivot post or a "threaded titanium insert", such as the one described above and illustrated herein. The articulating inserter 100 holds this post, enabling the cage to swivel or rotate, sometimes up to 90° relative to the shaft to move from an in-line, narrow insertion profile to a horizontal, transverse position. In some embodiments, the articulating inserter 100 often permits the surgeon to "steer" the spacer 90. For example, some systems allow the spacer 90 to rotate from a posterior position toward the contralateral side, with the articulation controlled by a thumbwheel or lock on the proximal end of the instrument. Incertain embodiments, the angle of the spacer 90 relative to the shaft (inserter 100) can be locked, adjusted, or re-positioned by tightening or loosening a "screwcap" or "knob" at the handle of the instrument, providing stability when the desired angle is achieved. The articulating inserter 100 usually allows the spacer 90 to be inserted while in line with the shaft (for narrow, minimally invasive entry) and then angled to a " T" shape relative to the shaft for final positioning.

[0074] The type and functionality of the articulating inserter 100 also depends on the type of spacer 90 being delivered. For example, bullet spacers are inserted straight into the disc space, and are thus rigidtly attached to the inserter, and can be easily navigated. Banana spacers are placed with an “articulating” inserter, which has a hinge that allows the cage to rotate into the appropriate position. Due to the articulating nature of the insertion technique, banana spacers are technically more challenging to insert.

[0075] There are thus several mechanism that form a part of the articulating inserter 100 to impart the desired controlled movements of the spacer 90 relative to the articulating inserter 100. For example, there is a rotatable threaded main shaft that detachably connects the spacer 90 to the articulating inserter 100. There can also be provided either a passive or active mechanism for articulating the spacer 90 relative to the articulating inserter 100. Several exemplary mechansims are described herein.

[0076] Figs. 5 and 6 show the basic working components of one exemplary articulating inserter 100 according to one embodiment. The articulating inserter 100 has a shaft 110 that is connected to a handle portion at the proximal end of the articulating inserter 100 and has a first longitudinal bore 113. A threaded rod 115 extends through the the first longitudinal bore 113 of the shaft 110 and has a first knob 117 at a proximal end, and a threaded end 118 at its distal end. The threaded rod 115 is axially movable relative to the shaft 110 through rotation of the first knob 117. In this manner the threaded end 118 of the rod 115 can be threaded into the threaded opening 96 of the post 95 by rotation in a first direction, or be unthreaded from the threaded opening 96 of the post 95. In this way, the spacer 90 is detachably connected to the articulating inserter 100 to allow for secure delivery of the spacer 90 to the surgical site.

[0077] As mentioned, the second main mechanmism that is part of the articulating inserter 100 is in the form of an articulation mechanism for articulating the spacer 90 relative to the shaft 110. There are many different mechanical mechanims that are configured to translate a first motion, such as a motion at the handle portion, into a second motion in the form of a controlled rotation of the spacer 90.Figs. 5 and 6 illustrate one working example of such an articulation mechanism. The articulating inserter 100 has a gear mechanism that is configured to articulate the spacer 90. Within the shaft 110 there is a housing open space or a second longitudinal bore. An elongated gear shaft 131 extends through the the open space or the second

[0078] longitudinal bore of the shaft 110 and has a second knob 134 at a proximal end, and a bevel gear 135 at an opposite distal end. Rotation of the second knob 134 causes rotation of the bevel gear 135. As is known, a bevel gear 135 works by using cone-shaped, interlocking teeth on gears mounted on intersecting shafts (often at 90 degrees) to transmit power, changing the direction of rotation and allowing for speed / torque adjustments, much like a standard gear but with an angular shift. In the illustrated embodiment, the head 92 has a fixed ring shaped gear 140 formed along the top surface of the body of the spacer 90. The gear 140 is an annular shaped gear that is concrentic with and surrounds the bore 93 in which the post 95 is located. Since the gear 140 is fixed relative to the body of the spacer 90, rotation of the gear 140 is directly translated into rotation of the spacer 90. The teeth of the gear 140 are configured to mate with the teeth of the bevel gear 135 and therefore, rotation of the bevel gear 135, due to rotation of the second knob 134, directly imparts a rotation of the gear 140, thereby articulating the spacer 90 about a center pivot axis through the bore 93.

[0079] It will be appreciated that the first and second knobs 117, 134 are independent from one another and can be arranged in a side-by-side orientation at the proximal end of the handle portion. The knobs 117, 134 can include indicia to differentiate the two.

[0080] Alternatively, the two knobs 117, 134 can be at two different longitudinal locations along the handle portion with one knob being at the proximal end of the articulating inserter 100, with the other one being distally spaced from the one knob (i.e., longitudinally offset knobs).

[0081] It will also be apparent that the second knob 134 could be positioned along the side of the handle portion spaced from the first knob 117 as shown in Fig. 6. In that case, an additional gear mechanism, such as another bevel gear arrangement can be provided to translation rotation of the second knob 132 into rotation of the elongated gear shaft 131. For example, if the second knob 132 is along the side of the handle portion, the second knob can be connected to a short side shaft 133 that has a second bevel gear 137 at its end and the proximal end of the elongated gear shaft 131 has a gear 139 at its proximal end that meshes with the second bevel gear 137. The second bevel gear 137 and tliis other gear are thus at 90 degrees relative to one another. This arrangement of the second knob 134 on the side thus uses two bevel gear arrangements to translation rotation of the second knob 134 into rotation of the spacer 90.Other types of mechanisms for articulating the spacer 90 can be in the form of a pusher / puller, the action of which causes and / or permits articulation of the spacer 90 realtive to the shaft 110.

[0082] In yet another embodiment, for an inserted design where the articulation occurs at the spacer (cage) itself, the spacer rotates in specific discrete steps. There are many possible ways to implement this function, one of which is illustrated in Figs. 8A and 8B.

[0083] In another embodiment, the inserter attaches to a wheel on the spacer, and the spacer can rotate around that wheel. The spacer can be locked into a specific orientation by being pulled forcefully against the inserter 101 and the rotation is limited due a friction fit. Thus, the spacer is rotated to a desired position and can be locked in place. The other component of the present system is a means / mechanism for detecting (sensing) the position of the spacer relative to the inserter, with such mechanisms being described below.

[0084] Figs. 7A-7E illustrate another embodiment of an articulating inserter 200. The articulating inserter 200 includes an elongated shaft 210. Similar to the previous embodiment, the shaft 210 includes a first longitudinal bore 212 that contains a threaded rod 214. The threaded rod 214 has a first knob 216 at a proximal end, and a threaded end 218 at its distal end. The threaded rod 214 is axially movable relative to the shaft 110 through rotation of the first knob 216. In this manner, the threaded end 218 of the rod 214 can be threaded into the threaded opening 96 of the post 95 by rotation in a first direction, or be unthreaded from the threaded opening 96 of the post 95. In this way, the spacer 90 is detachably connected to the articulating inserter 100 to allow for secure delivery of the spacer 90 to the surgical site.

[0085] In order to articulate the spacer 90, the inserter 200 has a rotatable outer geared sleeve 220. The sleeve 220 is hollow and surrounds the shaft 110 and rotates relative thereto. The distal end of the sleeve 220 is a toothed construction in that there are a plurality of teeth 222 (formed circumferentially). The head of the spacer 90 includes a toothed portion 225 with teeth that mesh with the teeth 222. Fig. 7A shows the sleeve 220 and shaft 110 disengaged from the spacer 90, while Fig. 7B shows meshed engagement between the two. As with the previous embodiment, the teeth 222, 225 mesh and rotation of the sleeve 220 is translated into rotation of the spacer 90 (e.g., bevel gear arrangement).

[0086] A proximal end of the sleeve 220 can include a handle or lever 229 that assists the user is rotating the sleeve 220 relative to the shaft 110. The relative position of the lever 229 relative to the shaft 110 indicates the degree of articulation of the spacer 90. Indica can be on the shaft 110 to identify the degree of rotation of the sleeve 220 and thus the degree ofrotation of the spacer 90. Figs. 7C-7E show different degrees of articulation of the spacer 90 resulting from rotation of the sleeve 220.

[0087] Lock Mechanism

[0088] In addition, the articulating inserter 100 can and preferably does include a lock mechanism for locking the articulation of the spacer 90 relative to the shaft 110. The lock mechanism is accessible by the operator (surgeon) along the articulating inserter 100 and when manipulated can both lock the articulation mechanism and unlock the articulation mechanism. There are are variety of different lock mechanisms that are suitable for use in the present device. For example, one type of lock mechanism can be in the form of a brake or a clamp or compression lock. In one embodiment, the lock mechanism can act directly on the second knob 134 to prevent its rotation or in another embodiment, the lock mechanism can act directly on the elongated gear shaft 131. In both designs, the rotation of the elongated gear shaft 131 results and thus, the articulation of the spacer 90 is halted and prevented.

[0089] For example, a locking sleeve or collar can be designed to act on the second knob 134. The locking collar can be in the form of an axial pull-to-lock / push-to-lock sleeve. In this configuration, the locking collar sits around the knob and the locking collar slides forward / backward to engage a flat or keyway on the knob hub. When engaged, rotation is block. The operator simply pulls the locking collar to free and unlock the knob and pushes the sleeve to lock the knob. The locking collar can also incorporate a spring to bias it in one direction (one state).

[0090] Alternativelty, the lock mechanism can be a radial push button pin lock. A button on the side of the knob actuates a spring-loaded pin. The pin enters a slot or hole on the underlying hub to prevent knob rotation.

[0091] Alternatively, as mentioned, the lock mechanism can act directly on the elongated gear shaft 131. For example, an axial key engagement lock can be provided in which the elongated gear shaft 131 has a keyed flat, slot, or hex feature. A locking member, such as a clamp or locking sleeve slides axially to engage a mating key that prevents rotation of the elongated gear shaft 131. For example, the shaft 131 can have a hex shape and the locking mechanism is a partial hex shaped clamp that can slide into engagement with the shaft 131, thereby allowing axial movement of the shaft 131 but no rotation of the shaft 131. In another design, the lock mechanism can be in the form of a friction band or split-ring brake. A flexible band or split ring sits concentrically around the elongated gear shaft 131 and a knob or the like tightens the band (like a miniature hose clamp). This action clamps the elongatedgear shaft 131 and stops rotation. In yet another embodiment, the lock mechanism can be a pawl-and-detent / radial pin lock. For example, the elongated gear shaft 131 has radial notches, detent pockets, or serrations and a spring-loaded pawl, ball detent, or locking pin drops into the notches. When engaged, the elongated gear shaft 131 cannot rotate.

[0092] In Fig. 5, the lock mechanism is generally shown at 160.

[0093] Tracking of Articulated Interbody Spacer (Cage)

[0094] The present disclosure defines a method and mechanism by which an articulated interbody cage, such as spacer 90, can be tracked by a stereotactic navigation system, such as navigation system 10. Broadly speaking, the present disclosure describes methods and mechanisms by which the articulating inserter can be configured to communicate the position or angle of the articulation of the spacer 90 to the navigation system 10.

[0095] Generally, there are two ways that the articulation can occur:

[0096] 1) cage articulation: The articulation can be at the junction of the implant and the inserter. This means that there are no moving parts to the inserter. The implant can rotate when the articulation is unlocked. This is analogous to loosening your grip on a tennis racket and allowing the handle to spin in your hand. This is the most common way articulated TLIF inserters on the market function today. This type of articulation allows free rotation of the cage around the articulation but it can be more challenging to “know” the exact position of the cage;

[0097] 2) inserter articulation: the articulation can be built into the end of the inserter. This means that the end of inserter is always at a fixed angle with the cage, and the tip of the inserter can change angles. The angle of the articulation can be precisely controlled by the inserter: however, this requires a larger and bulky inserter tip.

[0098] It will also be appreciated that the disclosed method and mechanisms, by which the inserter can be configured to communicate the position or angle of the articulation to the navigation system, are intended and designed so as to be configurable for use in commercially available inserters, as well as those described and illustrated herein. Accordingly, the teachings of the present disclosure are to be broadly construed and are not limited to the specific embodiments described and illustrated herein.

[0099] Broadly, the present disclosure is directed to distal and handle-based tracking mechanisms for articulating interbody devices (i.e., the spacers / cages) that each is configured to detect the position of the spacer relative to the inserter instrument (e.g., the angle of articulation is detected / sensed). Thus, the tracking mechanism can be considered to be aposition indicator and can either be in analog form or in digital form and preferably, as described herein, the sensed rotational information (i.e., the detected angle of articulation of the spacer) is transmitted to the navigation system 10.

[0100] In one embodiment, the rotational information can be represented in an analog fashion using a dial or indicator that is part of or associated with the articulating inserter. This information can then be communicated to the navigation system 10. One method would simply be verbal communication, as the surgeon reads out “position 1”, and the angle of the instrument can be adjusted on the navigation system 10 by an operator. In this analog embodiment, the articulation mechanism is designed so that the allowable angles of the spacer 90 are characterized by being discrete “steps” which can be easily communicated, for example 10-degree increments. As the spacer (cage) 90 articulates into each one of these positions ranging from 0 to 90 degrees, a dial or indicator on the handle can indicate the degree of articulation. This position can then be communicated to the navigation system 10 to reflect the degree of articulation of the spacer 90 and as also described herein, the navigation system 10 is configured to superimpose a computer-generated image of the spacer 90 on the display image of the surgical site. The operator (surgeon) would initially insert the spacer (cage) 90 in position 0 (straight). The operator would articulate the handle to position 1 (10 degrees) and lock it into the new position.

[0101] This information would be communicated to the navigation system 10 to reflect the updated implant / inserter geometry. The surgeon can then further insert the spacer 90 and rotate it. The operator would then articulate the handle to position 2 (20 degrees) and lock it into the new position. This information would be communicated to navigation system 10 to reflect the updated implant / inserter geometry. This process is continued into the desired position is reached.

[0102] In one embodiment, a knob that is part of the articulation mechanism can itself can have indicia (markings) that correspond to different degrees of rotation of the spacer 90. This way the operator can determine the degree of rotation by observing the position of the knob.

[0103] Alternatively, the rotational position can also be represented digitally on the articulating inserter with electronics and a battery powered articulating inserter. This can be electronically transmitted to the navigation system 10 or communicated verbally by the surgeon with a digital readout. Fig. 11 shows a digital display on the inserter 100; however, the inserter 100 in Fig. 11 can also be in communication with the surgical navigation system 10 by a wired connector or wirelessly.As mentioned above, in one embodiment, the inserter attaches to a wheel on the spacer, and the spacer can rotate around that wheel. The spacer can be locked into a specific orientation by being pulled forcefully against the inserter and the rotation is limited due a friction fit. Thus, the spacer is rotated to a desired position and can be locked in place. Fig. 9 shows one mechanism for detecting a position of the spacer 90 relative to the shaft (i.e., the angle of articulation). There are serrations or teeth 190 on the spacer 90 that can match teeth (not shown) formed at the distal end of the inserter 100. Therefore, when tlie spacer 90 is tightened, there are discrete angles that the spacer 90 can be rotated at. The size and number of these teeth 190 can be varied depending on the number of steps that would be desired. Along the teeth 190, there is a striking element (depressing element) 195 that is in the form material that fills the space between two teeth 190. This striking element 195, as described below, is used to indicate the rotational position. The striking element 195 in turn will depress one ball bearing 193 on the tip of the inserter. As shown, within the housing of the inserter 100 there are a plurality of spring biased pins or levers 197, each of which corresponds to one position of the spacer 90 relative to the shaft. The levers 197 are generally parallel to one another with the ball bearings 193 at ends of the levers 197. As shown, the ball bearings 193 are located along an arc at the distal end of the shaft of the inserter 100.

[0104] The handle of the inserter 100 has a window 199 with markings, such as numbered positions. When the spacer 90 is rotated, the striking element 195 likewise rotates and will come into contact and depress one of the ball bearings 193. When the ball bearing 193 is depressed, the corresponding lever 197 appears within the window 199 at the stated position. Thus, the surgeon only needs to view the window 199 to see which lever end is visible and by looking at the position marker next to the lever 197 it can be determined what position the spacer 90 is at relative to the inserter 100. Additionally, if the serrations on the spacer 90 are not fully seated into the inserter 100, then none of the indicators will be depressed and visible, indicating to the surgeon that the spacer 90 is not properly rotated into one of the discrete positions. Alternatively, the position of the spacer 90 can be detected using a gear system that reflects the position of the rotational position of the spacer 90. Alternatively, the position of the spacer 90 can be detected using a thin depth gauge type device inserted through the handle that contacts the spacer 90 to determine the amount it has rotated.

[0105] Accordingly, the above description describes a device and system (e.g., instrument plus implant) that allows for the position of the implant relative to the instrument to be relayed to the user and permits a surgical navigation system to be used to track the position ofthe implant. As mentioned above, since the navigation system can precisely track the handle of the instrument and the disclosed mechanisms allow for the position of the implant relative to the handle of the instrument to be determined, these two bits of information allow for the precise tracking of the implant.

[0106] Broadly speaking, the above embodiment illustrates an implant (e.g., TLIF spacer / cage) and an instrument (e.g., inserter) that are designed to complement one another and permit movement of the implant relative to the instrument to be monitored and positioning information can transmitted to the user that is within an acceptable tolerance that allows the user to the disclosed system with a surgical navigation system, such as stereotactic navigation.

[0107] Stick Indicator

[0108] One simple position indicator for use in determining the angle of articulation of the spacer 90 includes the housing (shaft) of the articulating inserter having an elongated slot that is open at the proximal end of the housing. The distal end of the slot is open at the distal end of the housing / shaft and is thus in communication with the head of the spacer 90. The slot can have a T-shape. The head of the spacer 90 has a feature, such as a curved catch or angled ramp, that is positioned below the distal end opening of the slot. The spacer 90 pivots about the post 95 as discussed herein.

[0109] A stick indicator 300 is slidingly received within the slot. The stick indicator 300 has an elongated shape and along its top end there are markings 302 that correspond to different degrees of articulation of the spacer 90 relative to the shaft of the articulating inserter 100. The values of the markings are downwardly decreasing in that the highest value is at the top of the stick indicator and the lowest value marking is furthest from the top of the stick indicator.

[0110] In this design of a position indicator, the operator (surgeon) reads the stick indicator outside of the patient, such as at a read line 305. The way that this position indicator works is that the spacer 90 is articulated at the site, such as by applied external forces, and to read the angle of articulation, the operator slides the stick indicator downwardly in the slot until the distal end of the stick indicator contacts the curved catch / ramp of the head of the spacer 90. Once resistance is felt by the operator, this is indicative that the distal end of the stick indicator has contact the spacer 90 (i.e., contacted the catch). Once the stick indicator contacts the spacer 90, the operator then reads the visible marking 302 which indicates the angle of articulation of the spacer 90. For example, the third marking may show a “60” or a“3” both of which reflect that spacer 90 is at a 60-degree angle relative to the shaft of the articulating inserter 100.

[0111] It will be appreciated that the more the spacer 90 is angled, the further in the slot the stick indicator can travel and this is reflected by the higher marking value being at the read line 305 of the housing. As the spacer 90 is manipulated further and the angle of articulation changes, the operator simply slides the stick indicator down until contact is made with the spacer 90 (as indicated by a feeling of resistance or bottoming out) and then, the operator views the marking that is at the read line 305 of the housing. This tells the operator at what angle of articulation the spacer 90 is relative to the shaft of the articulating inserter.

[0112] As mentioned previously, these analog readings can be conveyed to the operator of the surgical navigation system 10 who then can input the readings and the surgical navigation system 10, for example, at user interface 27, and system 10 then displays on the display 30 the current position of the spacer 90 at the surgical site (disc) by superimposing a virtual implant on the 2D or 3D model.

[0113] Figs. 8A and 8B illustrate a related concept in which the stick indicator 300 is inserted into a blind hole 85 that is formed in the body (head) of the spacer 90. The stick indicator 300 can be readily removed from the hole or bore 85, for example a loose friction fit can result between the distal end of the stick indicator 300 and the bore 85. Fig. 8A shows the spacer 90 in the initial position (0 degree) and Fig. 8B shows the spacer 90 in an articulated position. It can be seen, as the spacer 90 articulates (rotates), the stick indicator 300 slides further within the housing similar to what is described above and the operator views the marking that is at the read line 305 of the housing. This tells the operator at what angle of articulation the spacer 90 is relative to the shaft of the articulating inserter.

[0114] Optical Encoder

[0115] In yet another embodiment, shown in Fig. 10, a distal optical gray-code ring 400 can be used to determine the angle of articulation of the spacer 90. In this version, a small patterned ring 400 is placed on the spacer 90 that acts like a barcode. A tiny light and sensor 410 at the tip of the articulating inserter 100 read the pattern, which changes as the spacer 90 rotates. Because the pattern 400 is unique at each angle, the articulating inserter 100 instantly knows exactly how far the spacer 90 has rotated, even when the surgeon can’t see it. This concept is similar to shining a flashlight on a wheel with stripes so the tool can “read” its position.

[0116] In one embodiment, the pattern 400 can be directly printed on the head of the spacer 90 using biocompatibility print media.Tills embodiment thus uses an absolute optical encoder, specifically a gray-code- based system, where only one bit changes between adjacent values, to let the articulating inserter 100 know the spacer’s 90 angle as soon as the device powers up. Because the encoder reports an absolute position rather than counting incremental steps, it avoids cumulative error entirely. This embodiment uses different components on the spacer 90 and on the articulating inserter 100. On the spacer wheel or hub, there is a disposable code ring that carries laser-etched alternating absorptive and reflective tracks. The ring 400 typically has a plurality of concentric tracks that together encode between 64 and 128 unique angular positions; however, less is equally possible. For one application, the spacer’s 0-90° articulation is mapped to roughly ten discrete codes (for example, one every 10°). The ring 400 can snap onto the cage hub (head) using a keyed spline and leaves with the spacer / cage after implantation.

[0117] Fig. 10 shows the ring 400 in the form of a thin, circular code ring fixed coaxially to the spacer’s rotational axis, carrying multiple concentric tracks of alternating light and dark segments (representing reflective and absorptive regions) arranged in a gray-code pattern so that only one bit changes between adjacent angular positions.

[0118] Inside the distal nose of the articulating inserter 100, the sealed infrared emitter 410 (around 850 nm) and a matching photodiode array read the pattern on the ring through a sapphire or fused-silica window. A pair of O-rings can provide sealing equivalent to an IPX8 fluid-immersion rating, ensuring the optical system remains protected during use.

[0119] The inserter’s nosepiece can sit 0.5-1.0 mm from the ring surface so the optics stay in focus and avoid any accidental contact, even when the surgeon applies axial load. The optical subsystem uses a collimated LED with a narrow field of view and a molded light guide that helps reject stray operating-room light. The handle’s microcontroller contains a gray-code lookup table, allowing it to convert the optical pattern into an absolute 0-90° angle reading that is sent in real time to the navigation system 10. For sterility, the code ring 400 can be made from PEEK, a high-performance polymer commonly used in medical implants, paired with a laser-carbonized pattern or black-oxide coating on a 17-4PH stainless insert. The ring 400 is sterilizable and is intended for single use. On the inserter side, the optical window receives an anti-fog coating, and a small flush port allows a quick saline rinse if blood or debris accumulates.

[0120] During setup, “position 0“ corresponds to the spacer’s straight-ahead position. The firmware verifies the initial reading by checking against the two adjacent codes during the first articulation cycle.Distal Inductive PCB Resolver and Disposable Conductive Target Ring

[0121] In this embodiment, the spacer 90 carries a thin metal ring with special shapes on it, and the spacer’s tip has a small coil that creates a harmless electromagnetic field. As the spacer 90 rotates, the metal ring changes that field in predictable ways, and the articulating inserter 100 senses those changes. It’s similar to how an electric stove can detect a metal pot: no touching, just sensing through proximity. The system uses this to calculate the spacer’s angle while it’s inside the patient.

[0122] The above design relies on a contactless inductive angle-sensing principle, where a set of primary and secondary coils on a thin PCB generates and senses an electromagnetic field. As the spacer 90 rotates, a conductive pattern on the mating ring modulates that field in predictable ways. This gives the system a clean, absolute angle reading without needing optics or leaving any magnets behind, and it remains highly robust even when surrounded by surgical fluids. To implement this, each part carries specific hardware. At the inserter tip, there is a polyimide PCB that incorporates two sine / cosine receive coils and one transmit coil. The entire assembly is potted in medical-grade epoxy and sits behind a thin PEEK window for protection. On the cage hub, the system uses a laser-etched conductive target ring, made either from copper or a 316L stainless-steel shim. This ring has a sinusoidal sector pattern, locks mechanically to the hub, and is removed along with the cage after implantation.

[0123] Electrically, the system excites the coils at about 1-2 MHz, then demodulates the resulting sine and cosine signals and computes an arctan2 function to determine an absolute 0-90° angle, typically with better than 1° resolution. The signals travel up the inserter through a shielded twisted-pair cable to the handle’s microcontroller, and the line is filtered to reject electrical noise from monopolar electrocautery. Mechanically, the sensor maintains a small but reliable air gap (e.g., 0.25-0.75 mm) between the coil PCB and the conductive target ring. An axial compliance spring helps preserve this gap even when the surgeon applies axial load. The target ring carries either a two-lobe (2 -pole) sinusoidal pattern or, optionally, a four-lobe (4-pole) pattern if the design team wants even better linearity.

[0124] From a sterility and lifecycle standpoint, the target ring is single-use, while the coil PCB at the inserter tip is reusable for at least 100 cycles. For calibration, the system defines zero degrees at the straight-ahead position. Firmware performs a simple one-point linearization, and the design can optionally incorporate temperature compensation through a small NTC thermistor placed near the coils.Distal Micro-Switch Ladder

[0125] In this embodiment, the spacer 90 has tiny bumps or notches around its edge. As the spacer 90 rotates, a small pin in the articulating inserter 100 rides over those bumps, and each bump lines up with its own little switch inside the articulating inserter 100. When a bump lines up, a specific switch clicks, telling the articulating inserter 100, “I’m at this angle.” It’s like a combination lock where each notch activates a button. If the spacer 90 isn’t fully locked into one of those notches, no switch clicks, so the surgeon knows it’s not in a safe position. A micro switch “ladder” (often referring to a sequence or bank of switches) driven by a tooth / push pin cam is thus a mechanical-to-electrical actuation system. This mechanism relies on a rotating cam equipped with specific teeth or pins to precisely trigger one or more micro switches at designated intervals.

[0126] Accordingly, this concept uses a mechanical microswitch ladder driven by a tooth- or “pushpin ’’-style radial cam to sense the spacer’s articulation angle. The idea is that the cage carries a set of small detent teeth, and as these teeth rotate relative to the articulating inserter 100, a follower pin rides over them and selectively actuates one of several sealed switches inside the articulating inserter 100. Each switch corresponds to a discrete angular step, so the articulating inserter 100 can report a clear electrical signal each time the spacer 90 clicks into a defined position. This avoids the need for optics or electromagnetics while still providing a digital, position-specific output.

[0127] From a placement standpoint, the cage hub carries the detent ring, which includes a deliberate “missing-tooth” index and a shallow radial cam profile. On the nose of the articulating inserter 100, a circular array of roughly nine to ten microswitches sits beneath a thin stainless cap. A single pushpin follower rides against the cage’s cam surface and lands over a unique switch at each detent position. When the geometry lines up, the pin depresses the corresponding tactile dome switch (or reed-style plunger), producing the electrical signal for that angle. Electrically, the system outputs a one-hot digital code, meaning one switch closes for each valid angular position. This can be conveyed using ten dedicated signal lines or collapsed into a 4-bit binary code through a diode matrix before being delivered to the handle’s microcontroller and then to the navigation system 10.

[0128] Mechanically, this type of detection system uses tooth spacing designed for 10° increments. The pushpin can feature a low-friction PTFE tip. A return spring ensures proper cam following. The missing-tooth feature corresponds to the 0° index position, and the firmware performs sanity-checks to catch impossible combinations or misalignment.

[0129] Because this is a fully mechanical-to-electrical interface, the switches are protected inside awelded cap, and the pushpin uses a miniature bellows seal (laser-welded) to prevent ingress of fluids while still allowing axial movement. If the spacer (cage) 90 is sitting between detents, meaning not fully locked into a tooth — no switch will be actuated. The firmware interprets this as a “not in discrete step” state, which is a useful safety indicator for the surgeon.

[0130] Handle-side Torsion-shaft and Angle Encoder

[0131] This embodiment, shown in Fig. 11, uses a long rod (torsion rod 505) inside the articulating inserter 500 that twists exactly the same amount as the spacer 90 rotates. That twisting motion is carried all the way back to the handle of the articulating inserter 500, where a small reader (encoder) 509 reads the degree of twist (torsion) and can displays the angle on a display 510 and internal processor unit / transmitter of the inserter 700 can send it to the navigation system 10. The surgeon is also provided with a simple dial 520 with markings, so they can see and feel what angle the spacer 90 is at. It's like turning a long screwdriver: the twist at the tip is copied precisely at the handle.

[0132] It will be appreciated that the inserter 500 can include one of the articulating mechanisms described herein for articulating the implant 90 at the end of the shaft of the inserter 500.

[0133] A torsion shaft handle encoder combines a rotary encoder (measuring rotation) with a handle designed for high torsional strength, often using robust materials like metal gears or specialized designs (hollow shaft with torsion arms) for industrial or automotive use, providing precise feedback for speed, position, or torque in demanding environments. These systems use a shaft (solid, hollow, or with a measuring wheel) connected to a sensor that generates electrical pulses, translating mechanical rotation into digital signals for control, with “torsion” referring to high torque handling or measuring shaft twist for torque sensing.

[0134] This sensor mechanism works by using a torsion shaft (essentially a long, slender mechanical linkage) to carry the spacer’s rotation from the distal hinge all the way back to the handle of the articulating inserter 500. The core idea is that as the spacer 90 articulates, a coaxial torsion rod or Bowden-style cable twists by the same amount, and that twist is read by an encoder in the handle of the articulating inserter 100. 'The handle therefore always sees exactly the same angular change occurring at the distal end.

[0135] To implement this technology, the system places specific hardware at both ends. At the distal hinge, a small gear segment engages the long inner torsion rod, which is typically made from spring steel. This rod runs the full length of the articulating inserter 500. At the handle, the shaft mates with a zero-backlash spur gear that drives an absolute magnetic oroptical encoder, often with a resolution around 12 bits. The same handle assembly also includes a detent dial with marked 10° increments, allowing the surgeon to feel and visually confirm articulation steps.

[0136] Mechanically, this mechanism prioritizes eliminating play or “slop” in the system. The drive components use preloaded bearings and an anti-backlash split gear, which together keep total lash under 1°. This ensures that whatever angle the implant reaches at the distal hinge is faithfully transmitted up to the handle without lag or drift. Calibration is straightforward: when the device is placed into its straight position, both the dial and the encoder are aligned at 0°, and a single button can synchronize this zero point with the navigation system 10.

[0137] One of the advantages of this mechanism is that it naturally offers redundancy. If the electronic encoder were ever to fail, the surgeon still has tactile and visual feedback from the detent clicks and printed angle markings on the handle. Conversely, if the surgeon happens to skip past one of the mechanical clicks, the encoder still provides a continuous,

[0138] high-resolution angle measurement to the navigation system 10.

[0139] Handl e-side Ratchet-Lever

[0140] For this embodiment, shown in Fig. 12, each time the surgeon moves a handle lever a 710 long the handle of the articulating inserter 700, it clicks into a slot. Each click moves the implant (spacer 90) a fixed number of degrees. Sensors in the handle count how many clicks have occurred and calculate the implant’s position. If s similar to a ratcheting wrench where each click equals a specific amount of rotation. The surgeon also feels and hears each click, giving them confidence that the implant moved exactly the expected amount even though they can’t see it.

[0141] A small reader (display) 720 displays the angle and internal processor unit / transmitter of the inserter 700 can send it to the navigation system 10.

[0142] A ratchet lever 710 with counted detents and acoustic / haptic feedback is a specialized control mechanism. These systems provide both a physical “click” (haptic) and often a sound (acoustic) for each movement step, allowing users to count positions without looking.

[0143] This embodiment uses a deliberate ratchet mechanism inside the handle of the articulating inserter 700, where each actuation of the lever produces a predictable, discrete angular change at the distal articulation. In other words, every time the surgeon moves the handle lever and it “clicks,” the implant reliably moves a fixed amount, typically 10° per click based on a designed gear ratio. Sensors inside the handle of the articulating inserter 700 count these clicks and convert them into a digital angle reading that the navigation systemdisplays. Because the surgeon both feels and hears each detent, the system provides strong haptic and acoustic confirmation that the articulation is progressing exactly as intended.

[0144] From a hardware standpoint, the handle of the articulating inserter 700 contains a chain of components: the lever drives a pawl, which in turn engages a ratchet wheel. A 36-tooth wheel is one example, where the handle’s full rotational range corresponds (through the mechanical linkage) to approximately 100° of distal articulation, making each tooth equal to one 10° step. The system also uses dual sensors: optical interrupters mounted at the pawl for counting direction and steps, and a Hall sensor or reed switch for detecting the home / index position.

[0145] The design incorporates a mechanical lock that ensures the cage cannot drift once a detent is engaged. In normal use, each click is positively held. But if the surgeon inadvertently forces the lever backward without releasing the pawl, a torque-limit clutch allows the pawl to slip by design, preventing incorrect counting while protecting the mechanism from overload. Calibration is simple: the system recognizes a distinct index pulse at the “0°” detent, and when the device is placed into that straight-ahead configuration, the microcontroller zeros its counter and the navigation system synchronizes to that position. From that point onward, each ratchet click corresponds to a known 10° increment, and the display updates accordingly.

[0146] Updating Navigation System with Positional Data of the Spacer

[0147] In accordance with the present disclosure, the position of the spacer 90 is detected using one of the position indicators / position sensors disclosed herein. In other words, the angle of articulation of the spacer 90 relative to the longitudinal axis of the shaft of the inserter 100 is determined using one of the position indicators / position sensors.

[0148] The detected position data from the position indicator or position sensor is then forwarded and / or transmitted to the surgical navigation system 10 for generating a visual representation of the angle of articulation of the spacer 90 on display 30. In the simplest sense, when an analog mechanism or even a mechanism with a digital display on the instrument (Fig. 11) is used to detect the angle of articulation of the spacer 90 relative to the surgical instrument (inserter), the detected position data (such as a position number corresponding to a degree of articulation) can be relayed to an operator of the surgical navigation system 10 for inputting into the surgical navigation system 10, for example, via user interface 27. The inputted detected position data is then used by the software of the navigation system 10 to then display the computer-generated (virtual) image of the spacer 90 within the virtual disc image on the display 30, with the computer-generated spacer beingshown at the detected angle of articulation relative to the shaft of the surgical instrument. In some embodiments, a signal is transmitted from the position determination mechanism or sensor (e.g., 410 and those of inserters 500 and 700) to computing device 20 via a wired and / or wireless link between the mechanism / sensor and computing device 20. Computing device 20 can, then, interpret the received signal to determine the angle of articulation of spacer 90 and, if necessary, update the display of the computer-generated (virtual) image of the spacer 90 within the virtual disc image on the display 30. As mentioned previously, traditional surgical navigation systems were limited to displaying the real-time position of the surgical instrument (inserter) on a 3D model of the surgical site or on a 2D or 3D image of the site, such as a preop CT scan image. While this is helpful, in the case of the TLIF procedure, it is also helpful for the surgeon to understand the real-time position and orientation of the implant (spacer / cage) at the implantation site (target disc). 'The present disclosure not only provides numerous mechanisms and techniques for controlled articulation of the implant relative to the insert but also provides a number of mechanisms and techniques for determining an angle of articulation of the implant relative to the inserter. These mechanism themselves are preferably in communication with the surgical navigation system 10 to cause the real-time position of the implant to be displayed on the 3D model of the surgical site. Thus, the display shows not only the position of the inserter but also the position of the implant that is at the distal end of the inserter by overlaying computer- generated images of the inserter and implant (i.e., virtual tool and virtual implant) onto the 3D model. Each time the implant is articulated, the new detected position data (i.e., angle of articulation) is transmitted to the software which then updates the position of the virtual implant, depicted by a graphic, on the display.

[0149] This technology is illustrated in Figs. 4A-4D. Fig. 4A shows the inserter 100 with the spacer (implant) 90 in the initial first (or default) position (0 degrees of articulation). Fig. 4B shows the inserter 100 with the spacer (implant) 90 in a second position (30 degrees of articulation). Fig. 4C shows the inserter 100 with the spacer (implant) 90 in a third position (60 degrees of articulation). Fig. 4D shows the inserter 100 with the spacer (implant) 90 in a fourth position (90 degrees of articulation). In each of these figures, the display 30 shows the real-time position of the inserter 100 and spacer 90 using computer generated tool and implant graphics (virtual implant) overlayed over a 3D or 2D model of the surgical site.

[0150] As mentioned herein, within the navigation system 10, the CPU executes code that interprets the position data of the inserter and the implant (spacer), correlates it with preoperative or intraoperative imaging datasets, and produces the superimposed graphic datadisplayed to the surgeon. The CPU 29 integrates input from the transmitter, receiver, and tracking camera 75 to produce a unified, navigable work environment in which the inserter 100 and implant 90 are shown in correct anatomical context. The CPU continuously synchronizes tracking information with the HD display 30, maintaining accurate and parallel representation between virtual and physical space. In this manner, the image acquisition and processing unit uses the cooperative functions of its constituent components (the navigation system 10, tracking camera 75, reference array 50, HD display 30, and CPU) to provide reliable and real-time visualization of instrument and implant positions during the surgical procedure.

[0151] It will also be appreciated that since the exact position and orientation (pose) of the inserter 100 is detected and then the angle of articulation is calculated, the software is able to rotate the virtual implant relative to the virtual tool to such the angled position of the implant.

[0152] In addition, Fig. 13A and Fig. 13B illustrate the HD display 30 at two distinct stages of system operation, demonstrating how the image acquisition and processing unit updates and adjusts the visual output in real time based on positional changes of the inserter 100 and implant (spacer / cage 90) (lateral view of surgical site). In Fig. 13 A, the HD display 30 shows only the spine graphic (virtual spine or captured spine image) 600 representing the patient’s anatomy prior to insertion of the inserter 100 and implant 90. At this stage, no superimposed graphic data is present because the tracking camera 75 has not yet detected position data associated with the reference array 50 and that attached to the instrument. Once the inserter 100 and implant 90 are introduced into the surgical field and the setup procedure is followed, as depicted in Fig. 13B, the tracking camera 75 acquires the corresponding three-dimensional spatial coordinates of the reference array 50 and the spatial coordinates of the surgical instrument (inserter 100) and conveys this information as position data to the CPU. The CPU then processes and correlates the received position data with the anatomical model, generating superimposed graphic data 601 that is layered onto the spine graphic 1060. The superimposed graphic data 601 in Fig. 13B consists of superimposed graphic data, identified as 100A, that corresponds to the real-time position of the inserter 100 and superimposed graphic data, identified as 90 A, that corresponds to the real-time position of the implant (spacer 90).

[0153] This transformation from Fig. 13 A to 13B visually demonstrates how the navigation system 10 continuously integrates new tracking information, updates the virtual representation of the inserter 100 and implant 90, and maintains accurate alignment between

[0154] 97the displayed graphics and the real-time orientation of the tracked components during the surgical procedure.

[0155] Fig. 14 is a flow diagram of a process 1400 of displaying the inserter 100 and updating the display of the implant 90 in accordance with one or more exemplary implementations of the present disclosure. Process 1400 can be executed using computing device 20 shown in Fig. 3

[0156] As illustrated in Fig. 14, process 1400 initiates with step S1401, where computing device 20 obtains data for an image of a surgical environment. In one or more exemplary implementations, the image is a spine graphic of a patient. In embodiments, the image can be a 2D and / or 3D image.

[0157] Process 1400 then proceeds to step S1402, where computing device 20 determines a position of surgical instrument 100. In one or more exemplary implementations, the position of surgical instrument 100 is determined using DRA 50, LEDs / markers 60, and camera 75 illustrated in Fig. 3 and described above.

[0158] Next, at step S1403, computing device 20 displays, at display 30 shown in Fig. 3, the image of the surgical environment (e.g., spine graphic) with an overlay of a graphical representation of instrument 100 at the position determined at step S1402. In embodiments, the graphical representation of instrument 100 can be display initially with a graphical representation of an implant, such as spacer 90, detachably coupled to instrument 100 in an initial position — for example, at 0 degree articulation relative to instrument 100.

[0159] Then, at step S1404, computing device 20 determines a change in the position of the implant (e.g., spacer 90) relative to instrument 100. In one or more exemplary implementations, the position change is a change in an angle of articulation of the implant relative to instrument 100 and is determined at computing device 20 based on a user input at user interface 27 resulting from a verbal relay, as described above. In some embodiments, the change is determined based on a signal received from instrument 100.

[0160] Next, at step S1405, computing device 20 updates the display at display 30 to indicate the changed position of the implant. In one or more exemplary implementations, the changed position corresponds to the change in the angle of articulation of the implant relative to instrument 100 and the graphical representation of the implant is updated at display 30 to an updated position to reflect the change in the angle of articulation.

[0161] In embodiments, computing device 20 can continually update the graphical representations of instrument 100 and the implant at display 30 based on up to the moment determinations of the instrument position corresponding to step S1402 and of the implantposition corresponding to step S1404 until the completion of a surgical procedure. It is to be understood that like numerals in the drawings represent like elements through the several figures, and that not all components and / or steps described and illustrated with reference to the figures are required for all embodiments or arrangements.

[0162] It will also be appreciated that one articulation mechanism for articulating the implant, as described herein, can be combined with one implant position detection mechanism described herein. For example, the patterned encoder technology described with reference to Fig. 10 can be implemented in the gear concept of Figs. 5 and 6, etc.

[0163] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. 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. It will be further understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0164] Also, the phraseology and terminology used herein is for tire purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having," "containing," "involving," and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

[0165] The subject matter described above is provided by way of illustration only and should not be construed as limiting. Various modifications and changes can be made to the subject matter described herein without following the example embodiments and applications illustrated and described, and without departing from the true spirit and scope of the present invention, which is set forth in the following claims.

Claims

What is claimed is:

1. A system for delivering an implant to a surgical site under surgical navigation guidance comprising:a surgical instrument that is configured to deliver the implant to the surgical site, the implant being detachably coupled to the surgical instrument, wherein the surgical instrument is configured to controllably articulate the implant relative to a longitudinal axis of the surgical instrument; anda mechanism that is configured to determine a relative position of the implant relative to the longitudinal axis of the surgical instrument and be conveyed to a user of the system;wherein the surgical instrument has a first trackable element which is configured to be detectable by a surgical navigation guidance system for allowing real-time tracking of the surgical instrument.

2. The system of claim 1, wherein the surgical instrument comprises an elongated inserter and the implant comprises a transforaminal lumbar interbody fusion (TLIF) implant.

3. The system of claim 2, wherein the implant articulates in discrete steps relative to the elongated inserter and the mechanism is configured to measure an articulation angle of the implant relative to the inserter.

4. The system of claim 2, wherein the implant includes a wheel and the inserter is coupled to the wheel and the implant rotates about a center axis of the wheel.

5. The system of claim 4, wherein the inserter includes a linkage to cause rotation of the implant.

6. The system of claim 4, wherein the surgical instrument includes a lock mechanism that is configured to lock the implant at a given articulation angle.

7. The system of claim 6, wherein the inserter is configured to permit axial movement of the implant in a direction toward a handle of the inserter to permit the implant to be locked in the given articulation angle by means of an established friction fit between the implant and the inserter.

8. The system of claim 1, wherein the mechani sm includes an indicator on a handle of die instrument to indicate an articulation angle position of the implant relative to the instrument.

9. The system of claim 8, wherein the implant includes a wheel and the inserter is coupled to the wheel and the implant rotates about a center axis of the wheel, and wherein die mechanism includes teedi formed on die implant, wherein w'itliin theteeth there is a striking element, the mechanism further including a plurality of spaced apart ball bearings that are at a distal end of the surgical instrument such that when the implant is articulated, the striking element presses down one ball bearing of the plurality of ball bearings, each ball bearing being operatively coupled to corresponding levers of the indicator such that the user can identify the articulation angle position of the implant based on which ball bearing is depressed and which lever is visible in a window of the indicator.

10. The system of claim 1, wherein the implant comprises a blind hole and the surgical instrument includes an elongated shaft with a channel that extends an entire length of the shaft and is open at proximal and distal ends of the shaft, the mechanism comprises a flexible stick indicator that has position markers at a proximal end thereof with a distal end of the flexible stick indicator being disposed in the blind hole, whereby as the implant articulates relative to the longitudinal axis of the surgical instrument, a visible length of the flexible stick indictor at the proximal end of the shaft decreases and the angle of articulation of the implant is determined by comparing a read line to tire position markers.

11. The system of claim 1, wherein the surgical instrument comprises an elongated inserter and the implant comprises a transforaminal lumbar interbody fusion (TLIF) implant, wherein the inserter is detachably coupled to the implant with a threaded rod and the inserter includes a first rotatable gear that detachably meshes with a second rotatable gear that is disposed along the implant such that rotation of the first rotatable gear is translated into rotation of the second rotatable gear resulting in articulation of the implant.

12. The system of claim 11, wherein the first rotatable gear comprises a bevel gear and the second rotatable gear comprises a ring gear.

13. The system of claim 11, wherein the mechanism comprises an optical mechanism that is configured to determine an angle of articulation of the implant relative to the longitudinal axis of the inserter.

14. The system of claim 13, wherein the implant includes a patterned optical code and the inserter includes at a distal end thereof an optical reader that is configured to reads the patterned optical code based on the read patterned optical code, the angle of articulation is determined by the mechanism.

15. The system of claim 14, wherein the mechanism includes a processor that receives position signals from the optical reader that correspond to different angles of thearticulation of the implant, the processor being configured to transmit the position signals to the surgical navigation guidance system.

16. The system of claim 14, wherein the patterned optical code comprises a ring on a head of the implant and the optical reader includes a light source and a light sensor.

17. The system of claim 14, wherein the optical reader comprises an infrared emitter and a matching photodiode array that is configured to read the patterned optical code.

18. The system of claim 14, wherein the patterned optical code is printed on a head of the implant.

19. The system of claim 1, wherein the surgical instrument comprises an elongated inserter and the implant comprises a transforaminal lumbar interbody fusion (TLIF) implant, wherein the inserter is detachably coupled to the implant with a threaded rod and the inserter includes a rotatable sleeve that has a toothed distal end and the implant has a toothed head, the toothed distal end selectively meshing with the toothed head such that rotation of the rotatable sleeve is translated into articulation of the implant relative to the longitudinal axis of the inserter.

20. The system of claim 19, wherein the mechanism comprises an optical mechanism that is configured to determine an angle of articulation of the implant relative to the longitudinal axis of the inserter, the implant including a patterned optical code and the inserter includes at a distal end thereof an optical reader that is configured to reads the patterned optical code based on the read patterned optical code, the angle of articulation is determined by the mechanism, wherein the mechanism includes a processor that receives position signals from the optical reader that correspond to different angles of the articulation of the implant, the processor being configured to transmit the position signals to the surgical navigation guidance system.

21. The system of claim 20, wherein the patterned optical code comprises a ring on a head of the implant and the optical reader includes a light source and a light sensor.

22. The system of claim 1, wherein the mechanism includes a torsion rod that is routed along a shaft of the surgical instrument and is detachably coupled to the implant, the torsion rod being configured to twist exactly a same amount as the implant articulates and a twisting motion of the torsion rod is carried all the way back to a handle of the surgical instrument, the handle including an encoder that reads a degree of twist of the torsion rod, thereby allowing the degree of articulation to be determined.

23. A computer-implemented method, comprising:obtaining, at a processor, first data for an image of a surgical environment;determining, at the processor, a position of a surgical instrument;displaying, at a display device, the image of the surgical environment and overlaying a graphical representation of the surgical instrument at die determined position of the surgical instrument, said graphical representation comprising a representation of an implant detachably coupled to the surgical instrument in a first position relative to the surgical instrument;determining, at the processor, a changed angle of articulation of the implant relative to the surgical instrument; andupdating, at the display device, at least the representation of the implant to a second position to indicate the changed angle of articulation.

24. The computer-implemented method of claim 23, wherein the changed angle of articulation is determined based on a user input via a user interface.

25. The computer-implemented method of claim 23, wherein the changed angle of articulation is determined based on a signal received from the surgical instrument.

26. The computer-implemented method of claim 23, wherein the image of the surgical environment is a spine graphic of a patient.

27. The computer-implemented method of claim 23, wherein the image of the surgical environment comprises a pre-operative 2D scan image.

28. The computer-implemented method of claim 23, wherein the pre-operative 2D scan image comprises a CT scan.

29. The computer-implemented method of claim 23, wherein the image of the surgical environment comprises a 3D model based on one or more pre-operative 2D scan images.

30. The computer-implemented method of claim 23, wherein the step of determining, at the processor, the position of the surgical instrument comprises using a surgical navigation guidance system.

31. The computer-implemented method of claim 30, wherein the surgical navigation guidance systems comprises a stereotactic navigation system.

32. The computer-implemented method of claim 23, wherein the step of determining, at the processor, the changed angle of articulation of the implant relative to the surgical instrument comprises the step of reading a patterned optical code on the implant using a an optical reader that is disposed at a distal end of the surgical instrument and based on the read patterned optical code, the angle of articulation is determined.

33. The computer-implemented method of claim 23, further including the step of: using an articulation mechanism that is part of the surgical instrument to controllably articulate the implant.

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