Prosthetic Disc Placement and Removal System

Abstract

A prosthetic disc placement instrument for implanting a prosthetic disc is provided. The placement instrument shaft has a distal end and a proximal end and an instrument handle with an activation mechanism located at the proximal end. A pair of grasping jaws located at the distal end of the instrument shaft are configured to move relative to each other to grasp a multi-component prosthetic disc in a non-articulated configuration. The grasping jaws are movable from a tightened position to a released position by the activation mechanism. When the grasping jaws are in the released position, a prosthetic disc pusher on the distal end of the instrument shaft moves distally relative to the pair of grasping jaws, and the pusher is configured to contact the prosthetic disc to fully disengage the prosthetic disc from the placement instrument. A prosthetic disc core removal instrument is also provided for retracting the plates of a prosthetic disc from each other to allow easier removal of the core.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 841,359, filed on May 1, 2019 (WSGR Docket No. 29850 - 736.101) and U.S. Utility Patent Application No. 16 / 861,079, filed on April 28, 2020 (WSGR Docket No. 29850 - 736.201), the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to medical devices and methods. More particularly, the present invention relates to prosthetic intervertebral discs and systems and methods for implanting prosthetic intervertebral discs. Background Art

[0004] Back pain imposes a significant burden on the health and productivity of people worldwide. According to the American Academy of Orthopaedic Surgeons, approximately 80% of Americans will experience back pain at some point in their lives. On any given day, it is estimated that 5% of the working population in the United States is unable to work due to back pain.

[0005] Common causes of back pain are injury, degeneration, and / or dysfunction of one or more intervertebral discs. Intervertebral discs are soft tissue structures located between each of the thirty - three vertebrae that make up the spinal column (vertebral column). Substantially, the intervertebral discs allow the vertebrae to move relative to each other. The spinal column and intervertebral discs are important anatomical structures as they form the central axis that supports the head and trunk, allow back movement, and protect the spinal cord that passes through the vertebrae near the intervertebral discs. As people age, the intervertebral discs begin to shrink. In some cases, they may completely collapse and cause the bones to rub against each other. This is also known as osteoarthritis.

[0006] When damaged intervertebral discs cause pain and discomfort to a patient, surgery is often required. Generally, surgical procedures for treating damaged intervertebral discs involve discectomy (partial or total removal of the intervertebral disc), often followed by interbody fusion of the upper and lower vertebrae adjacent to the intervertebral disc or implantation of a prosthetic intervertebral disc. Fusion is most commonly achieved by implanting a cage or spacer along with bone graft material to promote bone growth to fuse the adjacent vertebrae together. Generally, pins, rods, screws, cages (or fusers), and / or the like are placed between the vertebrae to serve as a support structure to hold the vertebrae and bone graft material in place while the bones are permanently fused together. Spinal fusion eliminates movement between the vertebrae. When movement is the source of pain, fusion is an option.

[0007] An alternative to spinal fusion that does not restrict patient mobility is total disc replacement (TDR), also known as total disc arthroplasty. TDR surgery involves removing the natural disc between vertebrae and replacing it with an artificial disc prosthesis. There are several types of disc prostheses currently available. For example, one type of disc prosthesis includes an upper prosthesis plate and a lower prosthesis plate that are positioned against and engage adjacent vertebral bodies, and a movable core positioned between these prosthesis plates. The core can be movable or fixed, metallic, ceramic, or polymeric, and typically has at least one raised outer surface that mates with a recessed pocket in one of the plates in a fixed core device. In a movable core device, one or both of the outer surfaces of the core can be curved. To implant these discs, the natural disc is removed and the vertebrae are separated or forced apart to fit the artificial disc in place. The plates can be inserted individually or together, with or without the core present. It is desirable to reduce the duration of the surgery by implanting the disc in an assembled configuration. However, when holding the disc for implantation, it is desirable to firmly hold the disc with a placement tool without damaging the disc or the surrounding anatomy, and to easily remove the tool from the disc in place.

[0008] Currently available prosthetic discs are held, delivered, and removed using a variety of different instruments and techniques. Challenges with these known instruments and techniques include inadvertently changing the position of the prosthetic disc during instrument disconnection or difficulty disconnecting the instrument from the prosthetic disc due to interference from the surrounding anatomy. There is a desire to provide a disc system with a simple placement instrument that easily and securely grasps the implant for insertion and then easily removes from the patient.

[0009] In addition, it is desirable to hold the disc in an articulated or angled insertion configuration within the implant instrument to prevent the need to overly distract the disc space.

[0010] In addition, there is a desire to provide a disc removal system that has instruments to more easily and quickly separate the components of the prosthetic disc for removal.

[0011] Accordingly, there is a need for an improved artificial disc placement and removal system that increases the speed and reliability of the surgical procedure.

[0012] Description of the Background Art. Various intervertebral disc prosthesis designs and implantation methods are described in U.S. Patent Nos. 7,442,211, 7,531,001, 7,575,599, 7,585,326, 7,637,913, 7,753,956, 8,206,449, 8,685,035, 8,764,833, 8,808,384, 9,011,544, and 9,351,846, and U.S. Patent Application No. 15 / 842,663, each of which is incorporated herein by reference in its entirety. Summary of the Invention

[0013] According to one aspect of the present invention, a prosthetic disc placement instrument includes: an instrument shaft having a distal end and a proximal end; an instrument handle having an activation mechanism located at the proximal end; and a pair of grasping jaws located at the distal end of the instrument shaft. The pair of grasping jaws are configured to move relative to each other to grasp a multi-component prosthetic disc in a non-articulated configuration. The grasping jaws are movable from a tightened position to a released position by the activation mechanism. When the grasping jaws are in the released position, a prosthetic disc pusher on the distal end of the instrument shaft moves distally relative to the pair of grasping jaws, and the pusher is configured to contact the prosthetic disc to completely disengage the prosthetic disc from the placement instrument.

[0014] According to another aspect of the present invention, a method of placing a prosthetic intervertebral disc using a single placement instrument includes the steps of: securing the multi-component prosthetic disc to the distal end of the placement instrument by grasping at least a portion of the multi-component prosthetic disc between the grasping jaws on the placement instrument; inserting the prosthetic disc into the disc space of a patient using the placement instrument; releasing the prosthetic disc grasping jaws by moving the grasping jaws from a tightened position to a released position via the activation mechanism on the placement instrument handle; and pushing the prosthetic disc out of the grasping jaws using the prosthetic disc pusher on the distal end of the instrument shaft, wherein the prosthetic disc pusher moves distally relative to the pair of grasping jaws when the grasping jaws are in the released position, and wherein the pusher is configured to contact the prosthetic disc to completely disengage the prosthetic disc from the placement instrument.

[0015] According to another aspect of the present invention, a prosthetic disc core removal instrument includes: a pair of core removal arms having inner surfaces shaped to substantially correspond to the outer periphery of a prosthetic disc core; a retraction wedge that tapers from a thinnest portion at a distal end to a thicker portion a distance from the distal end such that insertion of the retraction wedge between two prosthetic disc plates of the prosthetic disc retracts the plates away from each other to allow easier removal of the core; and a core removal instrument handle. The instrument handle is connected to the pair of core removal arms and the retraction wedge. The handle is configured to move the arms relative to each other to grip the core for removal and is configured to advance the retraction wedge to retract the plates away from each other to allow easier removal of the core. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments that utilize the principles of the invention, in the drawings:

[0017] Figure 1 is a perspective top view of a prosthetic disc placement instrument in a loaded position;

[0018] Figure 2 is Figure 1 a top view of the instrument of

[0019] Figure 3 is Figure 1 a side view of the instrument of

[0020] Figure 4 is Figure 1 a bottom view of the instrument of

[0021] Figure 5 is Figure 1 a top view of the instrument in a cleaning position;

[0022] Figure 6 is Figure 1 a top view of the inner push rod of the instrument of

[0023] Figure 7 is Figure 1 a top view of the outer handle and gripping assembly of the instrument of

[0024] Figure 8 is Figure 1 a top view of the distal end of the instrument in a loaded position or a tightened position;

[0025] Figure 9 is Figure 1 a top view of the distal end of the instrument in a released position;

[0026] Figure 10 Is Figure 1 A top view of the distal end of the instrument in the deployed position;

[0027] Figure 11 Is a perspective view of the distal end of an alternative embodiment of an intervertebral disc placement instrument;

[0028] Figure 12 Is Figure 11 A perspective view of the instrument, wherein the prosthetic disc is locked in place on the instrument;

[0029] Figure 13 Is Figure 11 A perspective view of the instrument, wherein the disc is in the released position;

[0030] Figure 14 Is Figure 11 A perspective view of the instrument, wherein the disc plate is in the lifted position;

[0031] Figure 15 Is Figure 11 A perspective view of the instrument, wherein the disc is in the deployed position;

[0032] Figure 16 Is a perspective view of a core removal instrument for grasping the core of a disc; and

[0033] Figure 17 Is Figure 16 A perspective view of the instrument, wherein the instrument removes the core. DETAILED DESCRIPTION

[0034] Properly positioning a prosthetic intervertebral disc in the spine is an important part of a successful total disc arthroplasty (TDR) procedure. The position of the implant within the intervertebral space affects range of motion, implant behavior, and clinical outcome. The proper position in the anterior / posterior direction between the vertebral bodies is particularly important, but can be difficult due to the surrounding anatomy. Surgeon experience, surgeon training, use of imaging modalities, and patient anatomy are all factors that can affect the accuracy of prosthetic disc placement.

[0035] The prosthetic intervertebral disc placement system according to the present invention includes a multi-component prosthetic disc and an associated placement instrument. The placement instrument securely holds the prosthetic disc for placement into the disc space and rapidly releases the prosthetic disc within the disc space at a desired location between the vertebral bodies. The rapid release is facilitated by providing an instrument with an ejector that aids in disengaging the prosthetic disc from the instrument.

[0036] An example of a prosthetic disc for insertion between adjacent vertebrae includes an upper plate, a lower plate, and a core between the upper and lower plates, such as the prosthetic discs described in U.S. Patent Nos. 8,808,384 and 10,206,785, the entire contents of which are incorporated herein by reference. The core is held between the upper and lower plates by retaining features and is designed to allow the plates to slide in the anterior / posterior and lateral directions on the upper and lower surfaces of the core and to allow the plates to articulate and rotate relative to each other and the core. The upper and lower plates are provided with side grooves, notches, slots, channels, or other features that can be grasped by a placement instrument.

[0037] Figure 1 A first embodiment of a prosthetic disc placement instrument 10 is shown, which is formed by a shaft 12, a distal actuator 14, and a proximal handle end 16. The proximal handle end 16 includes a grasping handle 18 and an actuation mechanism 20. A pair of grasping jaws 24 located on the end 14 are configured to move relative to each other to grasp a multi-component prosthetic disc. Preferably, the grasping jaws 24 grasp the prosthetic disc from the side in a non-articulated configuration such that multiple parts of the prosthetic disc can be placed simultaneously. By the actuation mechanism 20, the grasping jaws 24 can move from Figure 1 the shown loading position or grasping position to a tightening position, a release position, a pushing position, and a cleaning position. Figure 1 The shown loading position or grasping position has an actuation mechanism nut 32 that does not contact the handle 18, allowing the grasping jaws 24 to bend outward to receive the prosthetic disc. Once the prosthetic disc is in place between the grasping jaws 24, the nut 32 is tightened against the handle 18 to hold the disc in a tightened position in the grasping jaws. After placing the disc in the disc space, the nut 32 is loosened to a release position that appears the same as the loading position, and the grasping jaws 24 no longer tightly grasp the disc.

[0038] A prosthetic disc pusher 30 on the distal end of the instrument shaft 12 moves distally relative to a pair of grasping jaws 24 to contact the prosthetic disc, thereby causing the prosthetic disc to completely disengage from the placement instrument 10. The actuation mechanism 20 includes a nut 32 for opening and closing the grasping jaws 24 and a thumb-actuated button 34 for advancing the pusher 30.

[0039] Figure 2is a top view of the placement of the instrument 10, where the grasping jaws 24 are shown in the loading position or the grasping position. In the tightened position, the distal end 14 of the instrument looks the same, but since the nut 32 is tightened against the proximal end of the handle 18, the grasping jaws 24 firmly hold the disc. As can be seen through the window 36 in the handle 18, the shaft 12 is formed by an inner shaft 40 and an outer shaft 42. The inner shaft 40 has a threaded portion at the proximal end for receiving the activation mechanism nut 32. The inner shaft 40 is also connected to the ejector 30 at the distal end, and rotation of the nut 32 causes the inner shaft 40 to move within the outer shaft to loosen and tighten the grasping jaws 24. The inner cam surface 44 on the ejector 30 engages the outer cam surface 46 on the outer shaft 42 to tighten the grasping jaws 24 after rotation of the nut 32. The inner cam surface 44 and the outer cam surface 46 can be seen more clearly in Figure 6 and Figure 7 , which show top views of the inner ejector rod, the outer handle, and the grasping assembly of the instrument 10 in the disassembled configuration. Figure 7 also clearly shows the slot 52 in the outer shaft, which allows the grasping jaws 24 to move between the loose loading position and the tightened position by bending a portion of the shaft. Although the grasping jaws 24 are shown grasping the upper and lower plates at notches in the side surface of the plate, other grasping arrangements can be employed. For example, only one of the upper and lower plates can be grasped; the plates can be grasped at the upper or lower surface of the plate or at another grasping feature of the plate; or the grasping jaws can grasp the plate and / or the core of the prosthetic disc.

[0040] Figure 3 and Figure 4 are respectively Figure 1 side and bottom views of the instrument 10 in the same loading or release position, where the nut 32 is threadedly connected to the thread near the proximal end of the inner shaft 40. In the fully tightened position, the nut 32 will contact the proximal end of the outer shaft 42.

[0041] Figure 5 shows a top view of the instrument 10 in the cleaning position. In the cleaning position, the nut 32 is completely unthreaded or completely disengaged from the thread 54 of the inner shaft 40. However, the nut 32 does not fall off the instrument because the disc-shaped thumb button 34 on the inner shaft prevents it from completely separating from the instrument. In the cleaning position, all the components of the instrument 10 are connected and cannot be completely separated, and are in a loose configuration to allow cleaning fluid to pass through all the components of the instrument. The cleaning window 36 in the handle 18 and the additional cleaning window 50 in the outer shaft 42 ( Figure 3 ) and the slot 52 help to allow the cleaning fluid to circulate through all the components of the instrument, especially to circulate between the inner and outer shafts and inside the threads of the nut.

[0042] Figures 8 to 10A top view of the distal end of the instrument 10 in three different positions is shown, the three positions including a tightened position ( Figure 8 ), a release position ( Figure 9 ), and a deployment position ( Figure 10 ). In the Figure 8 tightened position, the nut pulls the inner shaft proximally, causing the inner cam surface 44 of the pusher to slide against the outer cam surface 46 of the outer shaft 42 so that the grasping jaws move towards each other in the grasping or tightened position. In the Figure 9 release position or disengaged position, the nut is released to allow the cam surfaces 44, 46 to disengage from each other and to allow the grasping jaws 24 to move away from the notch or groove in the side of the prosthetic disc. In the Figure 10 deployment position, the distal end of the pusher 30 serves both to further push apart the grasping jaws 24 and to push the prosthetic disc away from the instrument grasping jaws. By pressing the thumb activation button 34 at the proximal end of the instrument, the pusher 30 moves forward to the deployment position. Figures 8 to 10 The particular cam arrangement shown is merely an example of a cam system that can be used to move the grasping jaws 24 and the pusher 30 between the tightened position, the release position, and the deployment position. Additionally, the distal end of the pusher 30 can be configured to cooperate with any part of the prosthetic disc and apply a force to any part of the prosthetic disc to effect a desired separation of the instrument from the disc. For example, the distal end of the pusher can be configured to cooperate with the core, one or more plates, or both the core and the plates.

[0043] When the pusher 30 is in the Figure 10 shown deployment position, the pusher can be used to adjust the position of one or more components of the prosthetic disc or the entire prosthetic disc. For example, the distal end of the pusher 30 can be shaped to engage the upper and lower plates of the prosthetic disc to cause the upper plate and / or the lower plate to advance posteriorly by striking the proximal end of the instrument 10 with a mallet. Using the pusher 30 to advance the plates proximally either individually or together eliminates the need to use a separate final placement instrument to adjust the plates of the prosthetic disc to their final position between the vertebrae. In one example, the distal edge of the pusher 30 has a concave curvature to match the corresponding convex posterior edge of the upper plate and / or the lower plate.

[0044] Figures 11 to 15 Another embodiment of a placement instrument 200 having different structures of grasping jaws and a pusher is shown, and an example of the interaction of the placement instrument with a prosthetic disc 100 is shown. As Figure 12As shown, the prosthetic disc includes an upper plate 102, a lower plate 104, and a movable core (not shown) between the upper and lower plates. In the implanted configuration, the upper plate 102 and the lower plate 104 are hinged relative to each other, and when the prosthetic disc 100 is secured to the placement instrument 200, the upper and lower plates are locked in a non-hinged insertion position. The notches 106 on the sides of the upper plate 102 and the lower plate 103 are sized and shaped to receive the grasping jaws of the placement instrument.

[0045] Similar to Figure 1 the embodiment of, Figures 11 to 15 the placement instrument 200 includes an inner shaft and an outer shaft that move relative to each other. However, in the placement instrument 200, the inner shaft 240 is connected to the grasping jaws 224, and the outer shaft 242 is connected to the pusher 230. Figure 11 is a perspective view of the distal end of the placement instrument 100 without the prosthetic disc, showing the grasping jaws 224 formed on the inner shaft 240. The inner shaft 240 has a slit 252 that allows the grasping jaws 224 to bend between a tightened position or a locked position and a released position. In Figure 12 the tightened position, the grasping jaws 224 are pressed towards each other by sliding the inner shaft 240 distally within the outer shaft 242 (or sliding the outer shaft proximally on the inner shaft) so that the inner shaft cam surface 216 contacts the outer shaft cam surface 218. Although a single set of cam surfaces is shown, a pair of cam surfaces can also be used. For example, the cam surfaces can be provided on another grasping jaw on the left and right sides of the instrument or on the opposing top and bottom surfaces of the instrument. The grasping jaws 224 of the instrument 200 are configured to be released from the upper plate 102 and the lower plate 104 by moving laterally out of the notches 106 of the plates and / or by moving the plates apart and pulling the grasping jaws out between the plates.

[0046] Figure 12 is a perspective view of the instrument 200 with the prosthetic disc 100 locked in the instrument and fully tightened thereon by positioning the protrusions 220 at the distal ends of the grasping jaws 224 within and engaging the notches 106 in the plates 102, 104. As Figures 12 to 15 shown, the plates 102, 104 are arranged to be inserted in an angled or inclined configuration in which the plate edges at the rear side (farthest from the instrument) of the disc are closer together than the plate edges at the front side of the disc. This angled implantation position provides a wedge shape for lower force insertion. Figure 12 shows the cam surfaces 216, 218 of the instrument that are engaged to hold the prosthetic disc in a locked arrangement in a wedge shape for insertion.

[0047] Figure 13An instrument 200 is shown, where the inner shaft 224 begins to be pulled back within the outer shaft 242 to release the inward pressure on the protrusion 220 and allow the disc 100 to be released from the instrument 200. However, even though there is no inward pressure on the protrusion 220 to hold the disc on the instrument 200, it may not be easy to remove the instrument from the disc because the patient's surrounding anatomy at the implant site continues to prevent the protrusion 220 from completely disengaging from the notch 106 of the plate. In cases where the instrument 200 is not easily released from the prosthetic disc 100, a pusher 230 can be used to push the disc away from the instrument. The pusher 230 includes two wedge members 238 that pass between the plates 102, 104 to separate the plates and allow the plates to slide off the protrusion 220. The pusher 230 also has four disc contact surfaces 236 or abutment surfaces that engage the rear edges of the plates 102, 104 to separate the disc from the instrument. The disc contact surfaces 236 are preferably shaped to match the shape of the corresponding front edges of the disc. Figure 14 The instrument and the prosthetic disc are shown in a position where the plates are lifted off the protrusion 220 by the wedges 238 of the pusher 230, and the disc contact surfaces 236 of the pusher contact the disc for pushing.

[0048] Figure 15 The prosthetic disc 100 is shown in a pushed-out position where the plate notch 106 pops out of the protrusion 220, and the plate passes over the top and bottom of the protrusion of the gripping jaw 224. This allows the gripping jaw 224 to be pulled directly back towards the instrument and avoids any difficulty in disengaging from the instrument when the patient's anatomy prevents the gripping jaw from moving laterally or side-to-side within the disc space. In cases where the patient's anatomy does not prevent the gripping jaw 224 from moving laterally, the prosthetic disc 100 can be released from the gripping jaw by pulling the gripping jaw away from the disc without the need for a pusher.

[0049] The method of inserting a prosthetic intervertebral disc using the placement instruments 10, 100 described herein includes fixing the prosthetic disc to the instrument by tightening the instrument gripping jaws, inserting the prosthetic disc into the desired position between the vertebrae, releasing the instrument gripping jaws from the prosthetic disc, pushing the disc out of the instrument, and removing the instrument from the patient. The prosthetic intervertebral disc is surgically implanted between adjacent spinal vertebrae to replace a damaged disc. Those skilled in the art will understand that the damaged disc is partially or completely removed according to known procedures and the adjacent vertebrae are forced apart from each other before inserting the prosthetic disc to provide the space required for inserting the disc.

[0050] To securely attach the prosthetic disc in the placement instruments 10, 100, the protrusions of the instrument gripping jaws are seated in the upper and lower plate notches formed in the sides of the plate. By tightening the activation knob or other activation mechanism, which may be located at the proximal end of the handle or at other locations on the handle, the placement instrument is tightened around the disc. Once the prosthetic disc is loaded and tightened on the placement instrument, the disc is inserted between the vertebral bodies with the patient lying flat on the operating table and the instrument standing vertically up and down perpendicular to the body. If the prosthetic disc includes fins or teeth that require slots to be cut in the vertebral bodies, the disc is inserted by aligning the fins or teeth with the pre-cut slots. Using lateral imaging and tapping the distal end of the placement instrument with a mallet, the prosthetic disc is inserted into the space between the vertebral bodies until the upper and lower plates are at or within about 1 mm of the posterior edge of the vertebral bodies. When it is confirmed by X-ray or fluoroscopic imaging that the prosthetic disc is in the proper position, the placement instrument is removed by activating the activation mechanism. In one embodiment, the activation nut is rotated counterclockwise until the upper and lower plates are released by the gripping jaws. If the placement instrument becomes loose after the gripping jaws are released, the instrument can be removed. A slight side-to-side rocking motion can be used to remove the instrument. However, if the instrument is not easily removed, the ejector is activated to press the implant out of the instrument. Preferably, the activation mechanism for the ejector is manually activated without the need for a mallet. Figure 10 The ejector shown in the eject position can be used as a final placement instrument to adjust the position of one or more components of the prosthetic disc by advancing the disc backward. Once it is confirmed by lateral imaging that the disc has been inserted into the desired position, the retracted vertebrae are released, thereby causing the vertebrae to move together to hold the assembled disc in place.

[0051] In another version of the method for placing the prosthetic disc, the placement instrument is tightened around the disc in the manner described above. Once the prosthetic disc is loaded and tightened on the placement instrument, the disc is inserted between the vertebral bodies with the fins or teeth aligned with the pre-cut slots. Using lateral imaging and tapping the distal end of the placement instrument with a mallet, the prosthetic disc is inserted into the space between the vertebral bodies until the disc enters approximately half of the space as observed by lateral fluoroscopy, just over 50% of the anterior / posterior depth, or until the gripping jaws contact the vertebral bodies. When it is verified by X-ray or fluoroscopic imaging that the prosthetic disc is in the proper position, the placement instrument is removed. Figure 10 The ejector shown in the eject position is used as a final placement instrument to advance the prosthetic disc backward. The advancement can be performed by contacting one or both of the hinged plates of the prosthetic disc to advance the prosthetic disc together or by advancing the upper and lower plates sequentially to the final position.

[0052] In each embodiment of the placement instrument, the activation mechanism for the grasping jaws and the pusher may include any known handle-mounted activation mechanism for an instrument, including one or more rotatable knobs, movable levers, or other known mechanisms.

[0053] The prosthetic disc may be inserted laterally from the anterior, posterior, or posterior / lateral side of the patient's spine. In the illustrated embodiment, the intervertebral disc is designed for forward insertion into the intervertebral space. Although the intervertebral disc described herein is inserted anteriorly and shown in a size suitable for the cervical spine, the system may be modified to accommodate other locations in the spine (e.g., lumbar spine) and other implantation methods.

[0054] Sometimes, it is necessary to surgically remove an implanted prosthetic intervertebral disc from a patient. Currently, prosthetic intervertebral discs are removed using a variety of different instruments and techniques. Intervertebral disc removal surgery typically involves removing each plate from the vertebrae separately. One challenge with this known technique is that it is difficult to remove the plates without significantly retracting the vertebrae. Excessive retraction of the spine is undesirable due to stretching and damage to adjacent ligaments and structures. If the core is removed first between the plates, it will be much easier to remove the plates from the vertebrae and the retraction will be minimal. The core removal instrument 300 is as Figure 16 shown, the core removal instrument 300 can grasp and remove the core 108 between the upper plate 102 and the lower plate 104 of the disc 100.

[0055] Figure 16 and Figure 17 are perspective views of the core removal instrument 300 in the grasping position and the removal position, respectively. The core removal instrument 300 includes a pair of core removal arms 302, 304 that have inner surfaces shaped to substantially correspond to the outer perimeter of the core. As shown, the shapes of the two core removal arms 302, 304 may be mirror images of each other or may be different shapes. In one embodiment, the arms 302, 304 are tapered from their thinnest portion at the distal end to a thicker portion at a distance from the distal end to allow the arms to act like wedges to separate the plates 102, 104 a certain distance, which will allow the core to be removed from between the plates. The thicker portion of the arms 302, 304 is at least twice as thick as the thinnest portion, and the thicker portion is located at a distance from the thinnest portion that substantially corresponds to the diameter or maximum size of the core. Inserting the arms 302, 304 between the disc plates retracts the plates away from each other to allow easier removal of the core.

[0056] The arms 302, 304 of the core removal tool 300 are connected to an inner shaft 306 that slides within an outer shaft 308 of the core removal tool 300. Any known activation mechanism can be used to move the inner shaft and the outer shaft relative to each other, including knobs, levers, cams, ratchets, etc. The inner shaft 306 moves distally within the outer shaft 308 toFigure 17 The positions shown cause the arms 302, 304 to firmly hold the core for removal from the plate and cause the plates 102, 104 to abut the housing 310 at the end of the outer shaft. When the arms 302, 304 withdraw the core from between the plates, the housing 310 holds the plates in place.

[0057] In an alternative embodiment, the arms and retracting wedges of the core removal tool can be separate or distinct components that move relative to each other and can be actuated sequentially or simultaneously to grip the core and separate the plates. In one embodiment, the core removal tool sequentially allows the surgeon to grip the core, retract the plates, and then pull the core out from between the plates. Pulling the core out from between the plates can be performed by actuation of a mechanism of the handle or manually by the surgeon in the case where the core removal tool arms are gripping the core.

[0058] Modifications to the above-described components and methods for practicing the invention, combinations of the various feasible variations, and variations of aspects of the invention that are obvious to those skilled in the art are intended to fall within the scope of the invention as disclosed.

Claims

1. A prosthetic disc placement instrument, the prosthetic disc placement instrument comprising: An instrument shaft having a distal end and a proximal end; An instrument handle located on the proximal end and having an activation mechanism; A pair of grasping jaws located on the distal end of the instrument shaft, the pair of grasping jaws being configured to move relative to each other to grasp a multi-component prosthetic disc in a non-articulated configuration, the pair of grasping jaws being movable from a tightened position to a released position by the activation mechanism; And A prosthetic disc ejector located on the distal end of the instrument shaft, the prosthetic disc ejector moving distally relative to the pair of grasping jaws when the pair of grasping jaws are in the released position, and wherein the prosthetic disc ejector is configured to contact the multi-component prosthetic disc to cause the multi-component prosthetic disc to completely disengage from the prosthetic disc placement instrument.

2. The prosthetic disc placement instrument according to claim 1, wherein, The prosthetic disc ejector passes through at least a portion of the pair of grasping jaws to completely eject the multi-component prosthetic disc.

3. The prosthetic disc placement instrument according to claim 1, wherein, The instrument shaft includes an inner shaft and an outer shaft that are movable relative to each other.

4. The prosthetic disc placement instrument according to claim 3, wherein The pair of grasping jaws are connected to the outer shaft, and the prosthetic disc ejector is connected to the inner shaft.

5. The prosthetic disc placement instrument according to claim 1, wherein, The activation mechanism causes the pair of grasping jaws to move relative to each other by the action of one or more cams.

6. The prosthetic disc placement instrument according to claim 5, wherein, The one or more cams act between the prosthetic disc ejector and the pair of grasping jaws.

7. The prosthetic disc placement instrument according to claim 1, wherein, The prosthetic disc ejector is positioned outside the pair of grasping jaws.

8. The prosthetic disc placement instrument according to claim 1, wherein, The instrument is assembled in a configuration in which the pair of grasping jaws, the prosthetic disc ejector, and the activation mechanism cannot be removed from each other.

9. The prosthetic disc placement instrument according to claim 1, wherein, The prosthetic disc ejector is configured to contact the multi-component prosthetic disc to adjust the position of the multi-component prosthetic disc within the disc space.

10. A prosthetic disc placement system, the prosthetic disc placement system comprising the prosthetic disc placement instrument according to claim 1 and further comprising a multi-component prosthetic disc, the multi-component prosthetic disc comprising: An upper plate having an upper vertebral contact surface and a lower surface with a support surface on the lower surface; A lower plate having a lower vertebral contact surface and an upper surface with a support surface on the upper surface, wherein the upper plate and the lower plate are configured to be articulated relative to each other; A first notch and a second notch in the side surface of the upper plate and a third notch and a fourth notch in the side surface of the lower plate, wherein the first notch and the third notch are aligned with each other, the second notch and the fourth notch are aligned with each other, and the pair of grasping jaws are configured to grasp the upper plate and the lower plate in the non-articulated configuration by engaging the first notch, the second notch, the third notch, and the fourth notch.

11. A prosthetic disc placement system, the prosthetic disc placement system comprising the prosthetic disc placement instrument according to claim 1 and further comprising a multi-component prosthetic disc, the multi-component prosthetic disc comprising: An upper plate and a lower plate, wherein the upper plate and the lower plate are configured to be hinged relative to each other, and wherein the pair of gripping jaws are configured to grip the upper plate and the lower plate in the non-hinged configuration.

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