Spinal Fastening Element System

Abstract

It is known to use pedicle screws and connectors to treat spinal deformities. However, there are cases where the screws must be placed in a specific location relative to one another because otherwise the connector may not fit properly between them. Thus, a spinal fastening element system is provided that includes a guide tool 60 for aligning a screw path forming instrument 90 for use in forming a screw path in a vertebra 10 for subsequent placement of a pedicle screw 20, the guide tool including a guide tool stem 80 and a screw path forming instrument receiving section 70, the guide tool stem and the screw path forming instrument receiving section not moving relative to one another.

Description

[Technical field]

[0001] The present invention relates generally to a spinal fastening element system and method for installing pedicle screws and finds particular utility in spinal deformity correction surgery, although not limited to, through the use of surgically implantable devices. [Background technology]

[0002] Currently, spinal fixation elements, such as pedicle screws, are surgically inserted into the posterior elements (pedicles) of the spine as a means of providing mechanical support to the spine in the case of spinal fractures or as a means of correcting the shape of the spine in the case of surgical correction of spinal deformities, such as scoliosis.

[0003] A number of pedicle screws may be first inserted into various vertebrae of the spine, and then these pedicle screws may be connected to each other. Such a connection between two or more implanted pedicle screws may be achieved by a fixed approach, in which movement between the connected pedicle screws is prevented, or by a mobile approach, in which various desired degrees of movement between the connected pedicle screws are allowed. An example of a connection by a fixed approach is described in US2011034258(A1), which discloses a method for mounting the head of a pedicle screw to a bone anchoring device component for fixing the bone anchoring device component to the bone by a polyaxial approach. When such a connection between two or more implanted pedicle screws is achieved by a fixed approach, the pedicle screws may be connected together by a rod-type connector, for example, as disclosed in US2006036242(A1). It is known that when the connector is of rod type, the surgeon is usually required to bend the rod connector by various approaches during surgery to achieve a connector shape suitable for connecting two or more pedicle screws placed at various positions along the spine.

[0004] However, the connector may be of a more complex type than a rod, and such connector may not be adapted to bend during surgery to achieve a connector shape suitable for connecting two or more pedicle screws. Such complex types of connectors are common when the connection between two or more implanted pedicle screws is achieved by a movable technique that allows various desired degrees of movement between the connected pedicle screws. An example of a movable connection is described in the case of an artificial facet joint prosthesis, for example as described in US20060265074(A1).

[0005] Conventional devices for correcting spinal deformities involve the fixation of bone screws connected to rods via pivoting connections as described, for example, in WO2007014119A2. Furthermore, the use of ratchet mechanisms in conjunction with spinal implants is known from WO2010067113A1 and US2016338738(A1).

[0006] US Patent No. 2016338738(A1) describes a connector that can be used to connect individual pedicle screws together to correct spinal deformities over time by allowing controlled movement of the pedicle screws in the sagittal plane.

[0007] The connector comprises a stem and a pedicle screw receiving section, and a ratchet that controls movement of the stem relative to the pedicle screw receiving section. The pedicle screw comprises a threaded shaft and a connector stem receiving section. The connector stem receiving section may comprise a ball and socket joint that allows limited articulation of the connector stem relative to the shaft of the pedicle screw.

[0008] This approach allows for a range of relative motion between the pedicle screws and the connectors, thus providing an environment in which spinal deformity can be corrected over time.

[0009] In order to use a connector to connect two adjacent pedicle screws, the screws must be placed in a specific position, because otherwise the connector may not be properly fitted between them. This means that during surgery, the placement of the pedicle screws is only possible in a limited number of positions within a specific range relative to the adjacent pedicle screws. If the adjacent pedicle screws are placed in a position where a connector cannot be used to connect them together, or in a position that does not result in the required restriction of movement relative to the spine when they are connected to each other, the pedicle screws need to be moved. This is of course undesirable. Rather, it is important to place the pedicle screws in their correct positions on the first attempt.

[0010] Furthermore, pedicle screws are typically installed after pathways are created in the vertebrae. These pathways are created using a tool, such as a screw pathway creation instrument, and then the tool is removed after the pathways are created. If a connector connected to the first installed pedicle screw is used to guide the screw pathway creation instrument, the connector may be scratched or otherwise damaged. It is undesirable to use scratched or damaged connectors because they may result in tissue damage after surgery. Summary of the Invention [Problem to be solved by the invention]

[0011] It is therefore desirable to provide a tool to enable correct and precise positioning of pedicle screws during such procedures to avoid misplacement of screws, to avoid the later inability to connect the screws together using connectors, and to avoid damage to the connectors. [Means for solving the problem]

[0012] In a first aspect, the present invention provides a spinal fastening element system comprising a guide tool for aligning a screw path forming instrument for use in forming a screw path in a vertebra for subsequent installation of a pedicle screw, the guide tool comprising a guide tool stem and a screw path forming instrument receiving section, the guide tool stem and the screw path forming instrument receiving section being immovable relative to one another.

[0013] In use, after a first pedicle screw is placed in the vertebra, a guide tool may be connected to the first pedicle screw by insertion of the guide tool stem into the guide tool stem receiving section of the pedicle screw. The screw path forming instrument receiving section may then be used to receive one or more screw path forming instruments to create screw paths in the adjacent vertebrae. The screw path forming instruments may then be removed. The guide tool may then be removed. A second pedicle screw may then be placed in the screw path using a connector connected to the first pedicle screw and the second pedicle screw.

[0014] The guide tool may comprise a substantially radiolucent material so that during surgery, the screw path forming tool (which is not radiolucent) is not obscured by the guide tool, so that the exact location and orientation of the screw paths for the screws can be optimally selected with the use of radiography.

[0015] In contrast, if a non-radiolucent connector is used during surgery instead of a guide tool to serve as a guide for the preparation of a screw path for the screw, the non-radiolucent connector may obscure the radiological image of the spinal elements. This brings about the risk that the screw path for the screw may not be formed in the optimal position and / or with the optimal direction. This may result in damage to important structures of the spine, such as nerves or the spinal cord. If the guide tool is radiolucent, this problem may be avoided.

[0016] The thread path forming instrument receiving section may include a path open at both axial ends, the path including a bore, the bore having a longitudinal axis.

[0017] The pathway may be defined by a cylindrical wall, and the wall may include a slot that allows a guide wire to be inserted into the pathway in use. The guide wire may be used for placement of the pedicle screw. The guide tool stem may be configured to mate with a guide tool stem receiving section of an adjacent pedicle screw in use.

[0018] The spinal fastening element system may further comprise a screw track forming instrument for use in forming a screw track in the vertebrae for subsequent placement of a pedicle screw. For example, an awl may be used to create an initial depression or hole in the bone. The awl may then be replaced with a pedicle finder, both of which may be understood to be screw track or hole forming instruments.

[0019] The thread path forming tool may include a mating section that may have a size and shape that closely matches the size and shape of the hole in the path (the thread path forming tool receiving section) so that the mating section is receivable into the hole in the path during use to align the thread path forming tool.

[0020] The thread path forming instrument may include a depth limiter for limiting axial movement of the thread path forming instrument in one direction parallel to the longitudinal axis of the passage bore along the longitudinal axis when the thread path forming instrument is received in the thread path forming instrument receiving section. The depth limiter may be a collar disposed on the stem of the thread path forming instrument.

[0021] After the pedicle finder has been used to create an initial trajectory for the placement of the pedicle screws, it may be removed from the guide tool.

[0022] The spinal fastening element system may further comprise a screw path forming instrument receiving member including an attachment means for attaching it to the guide tool, the screw path forming instrument receiving member having an internal thread for rotationally receiving a screw path forming instrument for creating threads on an internal surface of a screw path created in the vertebra by the screw path forming instrument.

[0023] The attachment means may be a clamping mechanism that clamps the thread path forming instrument receiving member to the guide tool.

[0024] The spinal fastening element system may further include a screw path forming instrument having an external thread for rotationally receiving in the screw path forming instrument receiving member and for creating threads on an inner surface of the screw path created in the vertebra by the screw path forming instrument.

[0025] The thread trajectory forming instrument may include a guide tool mating section for aligning the thread trajectory forming instrument relative to the guide tool.

[0026] The guide tool mating section can have a size and shape that closely matches the size and shape of the hole in the passageway so that the guide tool mating section is receivable in use within the hole in the passageway to align the thread passage forming instrument.

[0027] In use, the thread trajectory forming instrument may be inserted into an opening in an axial end of the thread trajectory forming instrument receiving member distal from the guide tool and then rotated to move into a thread trajectory previously created in the vertebra by thread interaction, thereby creating threads on the inner surface of the thread trajectory. In this regard, the thread trajectory forming instrument may be considered a tap. The amount of insertion depth of the thread trajectory forming instrument into the vertebra may be controlled by the rotational movement of the thread trajectory forming instrument relative to the thread trajectory forming instrument receiving member.

[0028] The guide tool mating section can include a depth limiter for limiting axial movement of the thread-path forming instrument in one direction along the longitudinal axis parallel to the longitudinal axis of the passageway bore with the thread-path forming instrument received in the thread-path forming instrument receiving section of the guide tool. The depth limiter can be a collar on the stem of the thread-path forming instrument with a larger radius than the passageway bore such that it cannot enter the passageway.

[0029] The spinal fastening element system may further comprise a pedicle screw, the pedicle screw comprising a guide tool stem receiving section for receiving, in use, a guide tool stem of an adjacent guide tool. It is noted that the guide tool stem receiving section may also be known as a connector stem receiving section, since the guide tool stem receiving section may be used to receive a connector stem after the guide tool is removed.

[0030] The spinal fastening element system may further comprise a connector, the connector comprising a connector stem and a pedicle screw receiving section for receiving the guide tool stem receiving section of the pedicle screw in use, the connector stem and the pedicle screw receiving section being movable relative to each other in use about an axis parallel to the intersection of the coronal and transverse planes.

[0031] In use, the guide tool may be removed from the first pedicle screw and replaced with a connector. The connector stem may be inserted into the guide tool stem receiving section of the pedicle screw.

[0032] The connector may further comprise a ratchet for controlling movement of the pedicle screw receiving section relative to the connector stem in use about an axis parallel to the intersection of the coronal and transverse planes.

[0033] The connector stem may have substantially the same shape and size as the guide tool stem. The shape and size may be identical. In this regard, the guide tool may be selected from a range of guide tools, each having a different stem length. Additionally, the connector may be selected from a range of connectors, each having a different connector stem length. A connector from the range of connectors may include a connector stem having a shape and size equivalent to a guide tool stem from the range of guide tools. The shape and size may be identical. With this approach, the surgeon may select a guide tool including a guide tool stem having the most appropriate shape and size to ensure a correct connection between adjacent pedicle screws, and then replace the selected guide tool with an equivalent connector after forming a passage for a second pedicle screw using the selected guide tool.

[0034] The pedicle screw may include a threaded shaft and the guide tool stem receiving section of the pedicle screw may include a ball and socket joint for articulation of the guide tool stem relative to the shaft, which may allow for a wider selection of relative positions between the various installed components of the system.

[0035] In a second aspect, the present invention provides a method of installing a second pedicle screw in a second vertebra adjacent to a first vertebra, the first vertebra including a previously installed first pedicle screw, the method comprising: a) providing a guide tool according to a first aspect; b) inserting the guide tool stem into a guide tool stem receiving section of a first pedicle screw pre-installed in the first vertebra; c) placing a screw trajectory formation instrument receiving section at a selected location relative to the second vertebra; d) inserting a thread path forming instrument into the thread path forming instrument receiving section; and e) creating an initial hole in the second vertebra by operating a screw pathway preparation instrument; f) removing the thread path preparation instrument from the guide tool; g) mounting a thread path forming instrument receiving member onto the guide tool; h) inserting another thread path forming instrument into the thread path forming instrument receiving section; and i) operating a thread path forming instrument to create a thread path with an internal thread to the thread path created in the second vertebra; j) removing the threadpath forming instrument from the threadpath forming instrument receiving member; and k) removing the guide tool stem from the guide tool stem receiving section of the first pedicle screw pre-installed in the first vertebra; l) replacing the guide tool with a connector, the connector including a connector stem and a pedicle screw receiving section; m) inserting a second pedicle screw into the pedicle screw receiving section of the connector and into a threaded screw passage formed in the second vertebra; A method may be provided, comprising:

[0036] In the method of placing the second pedicle screw, the connector in step l) may be selected from a range of connectors each having a different connector stem length, such that the selected connector has the same stem length as the stem length of the selected guide tool.

[0037] In a third aspect, the present invention provides a method of installing a second pedicle screw in a second vertebra adjacent to a first vertebra, the first vertebra including a previously installed first pedicle screw, the method comprising: a) providing a guide tool according to a first aspect; b) inserting the guide tool stem into a guide tool stem receiving section of a first pedicle screw pre-installed in the first vertebra; c) placing a screw trajectory formation instrument receiving section at a selected location relative to the second vertebra; d) inserting a thread path forming instrument into the thread path forming instrument receiving section; and e) creating an initial hole in the second vertebra by operating a screw pathway preparation instrument; f) removing the thread path preparation instrument from the guide tool; g) removing the guide tool stem from the guide tool stem receiving section of a first pedicle screw pre-installed in the first vertebra; h) attaching a screw trajectory forming instrument receiving member to a connector, the connector including a connector stem and a pedicle screw receiving section; i) inserting a connector stem into a guide tool receiving section of a first pedicle screw pre-installed in a first vertebra; j) inserting a thread path forming instrument into the thread path forming instrument receiving section; k) operating a thread path forming instrument to create a thread path with an internal thread to the thread path created in the second vertebra; l) removing the threadpath forming instrument from the threadpath forming instrument receiving member; and m) removing the thread path forming member from the connector; n) inserting a second pedicle screw into the pedicle screw receiving section of the connector and into a threaded screw passage formed in the second vertebra; A method may be provided, comprising:

[0038] In this alternative method, instead of mounting the thread path forming instrument receiving member on the guide tool, the guide tool is removed and replaced with a connector and a thread path forming instrument receiving member is mounted thereon, in which case the connector stem operates in the same manner as the guide tool stem and does not move relative to the thread path forming instrument receiving section.

[0039] The step of removing the screw path forming member from the connector in step m) may be performed with the connector connected to the first pedicle screw or after it has been removed from the first pedicle screw.

[0040] Due to the fact that the thread path forming members are rigidly attached to the connector, there is no possibility that the connector will be damaged by the thread path forming tool.

[0041] In any of the methods of placing the second pedicle screw, in step a) the guide tool may be selected from a range of guide tools each having a different stem length.

[0042] The connector in step h) in the third aspect may be selected from a range of connectors each having a different connector stem length such that the selected connector has the same stem length as the stem length of the selected guide tool.

[0043] The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given for purposes of illustration only, and not to limit the scope of the invention. The reference drawings quoted below refer to the attached drawings. [Brief description of the drawings]

[0044] [Figure 1] FIG. 1 is a perspective view of three adjacent vertebrae including a spinal alignment device. [Diagram 2] FIG. 2 is a perspective view of two adjacent vertebrae including pedicle screws and corresponding guide tools. [Diagram 3] FIG. 3 is a perspective view of a range of different sized guide tools. [Figure 4] FIG. 4 shows two perspective views of the guide tool. [Diagram 5] FIG. 5 is a perspective view of a thread path forming tool and a guide tool. [Figure 6] FIG. 6 is a perspective view of the thread trajectory forming instrument receiving section and guide tool mounted therewith. [Figure 6a] FIG. 6a is a cross-sectional view of a thread path forming instrument receiving section and a connector attached thereto. [Figure 6b]FIG. 6b is a perspective view of the thread trajectory forming instrument receiving section with a thread trajectory forming instrument partially inserted therein. [Figure 7] FIG. 7 is a perspective view of a thread trajectory forming instrument. [Figure 8] FIG. 8 shows two perspective views of a pedicle screw. [Figure 9] FIG. 9 shows two perspective views of a portion of a pedicle screw. [Figure 10] FIG. 10 is a perspective view of a range of different sized connectors. [Figure 11] FIG. 11 shows two perspective views of the connector. [Figure 12] FIG. 12 is a perspective view of a pedicle screw and connector. [Figure 13] FIG. 13 shows two perspective views of the connector. [Figure 14] FIG. 14 is a perspective view of the connector and pedicle screw. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] The present invention will be described with reference to certain drawings, but the invention is not limited thereto, but only by the claims. The drawings described are schematic and non-limiting. Each drawing may not include all of the features of the invention, and therefore is not necessarily considered an embodiment of the invention. The size of some of the elements in the drawings may be exaggerated for illustrative purposes and may not be drawn to scale. The dimensions and relative dimensions do not correspond to actual reductions to implementations of the invention.

[0046] Moreover, terms such as first, second, third, etc. in the description and claims are used to distinguish between similar elements and are not necessarily used to describe an order in time, space, sequence, or in any other manner. It is understood that terms so used are interchangeable in appropriate circumstances and that other orders other than those described or illustrated herein are possible. Similarly, method steps described or claimed in a particular order may be understood to operate in a different order.

[0047] Moreover, terms such as top, bottom, above, below, etc. in this description and in the claims are used for descriptive purposes and not necessarily to describe relative positions, with it being understood that the terms so used are interchangeable in appropriate circumstances and further capable of operation in other orientations different from those described or illustrated herein.

[0048] It should be noted that the expression "comprises" used in the claims should not be interpreted as being limited to the means listed thereafter, and that these expressions do not exclude other elements and steps. It should therefore be interpreted as specifying the presence of the stated features, integers, steps, or components as they are mentioned, but without excluding the presence or addition of one or more other features, integers, steps, or components, or groups thereof. Thus, the scope of the expression "a device comprising means A and B" should not be limited to a device consisting only of components A and B. In the context of the present invention, it simply means that the relevant components of the device are A and B.

[0049] Reference herein to an "embodiment" or "aspect" means that a particular feature, structure, or characteristic described in connection with the embodiment or aspect is included in at least one embodiment or aspect of the invention. Thus, the use of the phrases "in one embodiment," "in an embodiment," or "in an aspect" in various places throughout this specification do not all relate to the same embodiment or aspect, but may refer to different embodiments or aspects. Furthermore, a particular feature, structure, or characteristic of any one embodiment or aspect of the invention may be combined in any suitable manner with any other particular feature, structure, or characteristic of another embodiment or aspect of the invention, in one or more embodiments or aspects, as would be apparent to one of ordinary skill in the art from this disclosure.

[0050] Similarly, it should be understood that in the present description, various features of the invention may be grouped together in one embodiment, figure, or description thereof for the purpose of simplifying the disclosure and aiding in the understanding of one or more of the various inventive aspects. However, this method of disclosure is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Moreover, the description of any individual figure or aspect is not necessarily to be considered an embodiment of the present invention. Rather, as the following claims reflect, inventive aspects may lie in fewer than all features of one foregoing disclosed embodiment. Thus, the claims following the detailed description are expressly incorporated herein into this detailed description, with each claim standing on its own as a separate embodiment of the present invention.

[0051] Furthermore, while some embodiments described herein may include some features included in other embodiments, it is intended that combinations of features of different embodiments be included within the scope of the present invention as understood by those skilled in the art to form yet further different embodiments. For example, in the following claims, any of the embodiments described in the claims may be used in any combination.

[0052] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the present invention may be practiced without these specific details. In other instances, well-known methods, structures, and techniques have not been shown in detail in order not to obscure an understanding of the present description.

[0053] In the discussion of the present invention, unless otherwise indicated, the disclosure of alternative values ​​for the upper or lower limits of a parameter of an acceptable range coupled with an indication that one of the values ​​is significantly more preferred than the other is to be construed as an implicit statement that each of the intervening values ​​of the parameter between the preferred and less preferred values ​​of the alternatives is itself preferred over the less preferred value, and over each of the intervening values ​​between the less preferred value and the intermediate value.

[0054] Use of the term "at least one" may mean only one in certain contexts. Use of the term "any" may mean "all" and / or "each" in certain contexts.

[0055] The principles of the present invention are explained below through detailed description of at least one drawing associated with exemplary features. It is clear that other configurations can be constructed based on the knowledge of those skilled in the art without departing from the underlying concept or technical teachings, and the present invention is limited only by the language of the appended claims.

[0056] In FIG. 1, three adjacent vertebrae 10a, 10b, 10c are shown with an attached spinal anchoring element system 5. The device comprises pedicle screws 20a, 20b, 20c, with each vertebra having one screw inserted therein for their posterior element (pedicle). Each pedicle screw comprises a connector stem receiving section 24a, 24b, 24c. The top pedicle screw 10c is inserted through a connector 100. The connector 100 comprises a head 120 and a stem 110 extending therefrom. The top pedicle screw 10c is inserted through the head 120 of the top connector 100. The stem 110 of the top connector extends downward and through the connector stem receiving section 24b of the middle pedicle screw 20b. Similarly, the middle pedicle screw 10b is inserted through the connector 100. The stem 110 of the central connector extends downward and through the connector stem receiving section 24a of the lowest pedicle screw 20a. The connector stem receiving section may be a socket.

[0057] With this approach, three vertebrae are connected together by a device 5. The device 5 is configured to control the relative movement of each vertebra with respect to the other vertebrae. This may be limited to control the relative movement of each vertebra with respect to only adjacent vertebrae. The following describes how the device 5 is installed and how it is used.

[0058] In Fig. 2 two adjacent vertebrae 10a, 10b are shown. The lowest vertebra 10a has a pedicle screw installed in its posterior element (pedicle). The pedicle screw 20 comprises a threaded shaft 22 and a connector stem receiving section 24. However, first a guide tool 60 is used instead of a connector. The connector 60 comprises a head 65 and a stem 80. The stem 80 is received in the connector stem receiving section 24, and therefore the connector stem receiving section 24 is referred to as the guide tool stem receiving section 24 when it is used for that purpose and as the connector stem receiving section 24 when it is used for that purpose.

[0059] With the stem 80 received in the guide tool stem receiving section 24, the head 65 is positioned adjacent to the top vertebra 10b. The guide tool 60 further comprises a channel in the head 65 defined by a cylindrical wall (the thread trajectory forming instrument receiving section 70) that extends axially parallel to the long axis of the installed pedicle screw 20, but posteriorly away from the posterior portion of the vertebra.

[0060] Although the pedicle screw 20 is shown as being placed with the long axis of the threaded shaft 22 substantially horizontal and through the center of the vertebra 10a, it is understood that it may be placed in other orientations, particularly if the spine has a unique curvature that is desired to be corrected.

[0061] The invention was conceived due to the need to be able to correct spinal misalignment over time. As explained above, in order to use a connector to connect two adjacent pedicle screws, the screws must be placed in a specific position, because otherwise the connector may not fit properly between them. This means that during surgery, the placement of the pedicle screws is only possible in a limited number of positions within a certain range relative to the adjacent pedicle screws. If the adjacent pedicle screws are placed in a position where the connector cannot be used to connect them together, or in a position that does not provide the required movement restriction to the spine when they are connected to each other, it is necessary for the pedicle screws to be moved. This is of course undesirable. Rather, it is important to place the pedicle screws in their correct position at the first attempt.

[0062] It is therefore desirable to provide a tool that allows for correct and precise positioning of pedicle screws during such procedures to avoid misplacement of screws, to avoid the later inability to connect the screws together using a connector, and to avoid damage to the connector.

[0063] This is accomplished through the use of guide tools 60 that provide a channel or thread path forming instrument receiving section 70 for receiving one or more thread path forming tools (drilling tools) for the creation of a channel for receiving the next pedicle screw. In use, the surgeon may select which guide tool 60 to use from a range of guide tools shown in FIG. 3. Each guide tool 60 includes a head 65 and a stem 80, but the length of the stem 80 and the angle at which it extends from the head 65 are different for each of the guide tools in the range. In this manner, the surgeon may select the most appropriate guide tool from the range to ensure that the thread path forming instrument receiving section 70 of the selected guide tool is adjacent to the portion of the vertebra where the next pedicle screw is to be placed, and that the long axis of its hole is at an optimal angle relative to the vertebra so that the pedicle screw 20 may be placed with the long axis of its threaded portion 22 at the proper angle relative to the vertebra.

[0064] FIG. 4 shows two views of one of the guide tools 60. A slot 82 can be seen extending axially through the head 65 and along the top surface of the cylindrical thread passage forming instrument receiving section 70. In use, this slot 82 allows a guide wire to be inserted into the passage 70. In use, such a guide wire can be passed through and along the central bore of the pedicle screw 20. Each stem 80 includes a step 81 that can be used to limit the insertion depth of the stem 80 into and through the pedicle screw guide tool stem receiving section. This is achieved by the step widening the top of the stem 80 between its distal end and the end proximal to the head 65, over approximately half its length along its length, so that it is too wide to fit through the guide tool stem receiving section 24 of the pedicle screw 20.

[0065] Threads 61 are visible on the inner surface of channel 70. They are optionally present. If they are present, they may cooperate with threads 62 that may optionally be provided on the outer surface of shaft 92 of a thread channel forming tool (tap) 99 (FIG. 7) for controllably inserting (by relative rotation thereof) the tool 99 into and removing it from bone.

[0066] 5 and can be seen to include an elongated shaft 92 with a handle 94 at one end and a relatively sharp point 96 in the form of an awl at the opposite end. Disposed on the shaft is a guide tool mating section 98, which is a cylindrical portion having an outer diameter substantially the same as the inner diameter of the thread trajectory forming instrument receiving section 70 in the guide tool 60.

[0067] Tool 90 is shown in combination with guide tool 60 with shaft 92 inserted through channel 70. The diameter of guide tool mating section 98 is substantially the same as the inner diameter of the channel of thread trajectory forming instrument receiving section 70, so that the long axis of shaft 92 is coaxial with the long axis of channel 70 of guide tool 60. This allows the surgeon to stably create a screw trajectory in the vertebrae at a selected location and orientation as determined by the selection of the guide tool and its location relative to the vertebrae.

[0068] The step 91 is placed on a length of the shaft 92 to prevent over-insertion of the awl through the guide tool and into the vertebrae. The step change increases the diameter of the shaft so that the diameter is larger than the inner diameter of the thread trajectory forming instrument receiving section 70 so that the shaft does not pass through the thread trajectory forming instrument receiving section 70.

[0069] Various thread trajectory tools (not all shown) may be used in sequence through the thread trajectory instrument receiving section 70 of the guide tool, for example, an awl followed by a pedicle finder and then a tap, as described below. After the initial hole has been formed in the vertebra, the thread trajectory tools may be removed from the guide tool 60.

[0070] The thread trajectory forming instrument receiving member 30 may now be attached to the guide tool 60. This may be done with the guide tool 60 in place with its stem inserted into the inferior pedicle screw, or after it has been removed from the pedicle screw. In the latter case, after attachment of the thread trajectory forming instrument receiving member 30 to the guide tool 60, the guide tool stem may be reinserted into the inferior pedicle screw.

[0071] 6, the thread path forming instrument receiving member 30 comprises a cylindrical body 31 including a bore extending along its entire length such that it is hollow. One end of the bore is visible to the right of the body 31 in the form of an opening 33. The thread path forming instrument receiving member 30 is shown attached to a guide tool 60 at its left end 32. The wall of the bore has threads 34 as will be described below.

[0072] 6a depicts an alternative manner in which the thread trajectory forming instrument receiving member 30 is mounted to the connector 100 instead of being mounted to the guide tool 60. The thread trajectory forming instrument receiving member 30 includes an end cap 35 rotatably mounted to a body 31 via cooperating threads 38. An inner member 36 is slidably disposed within a bore of the body 31. Rotation of the end cap 35 advances the inner member 36 towards the end 32 which, in use, is proximal to the vertebrae. This movement of the inner member can be used to clamp the head 120 of the connector 100 between the inner member and the proximal end 32.

[0073] Visible through are the internal threads 34 which may be engaged by threads 62 (FIG. 7) of a thread trajectory forming instrument.

[0074] An alternative thread path forming instrument receiving member 330 is shown in Figure 6b. It has the same features as the thread path forming instrument receiving member 30 shown in Figure 6a, such as an end cap 35 (not shown in Figure 6b) and the ability to clamp a connector head between the inner member and the proximal end. However, in this alternative, instead of the internal threads 34, a pin 337 is positioned to project radially into a bore in the cylindrical body 331.

[0075] In use, a thread trajectory forming instrument 399 (only a lower half section is shown for clarity of illustration) may be inserted into the opening 333 of the thread trajectory forming instrument receiving member 330. The instrument may then be rotated by hand such that the external threads 362 of the thread trajectory forming instrument 399 engage and cooperate with the pin 337. In this manner, a thread forming means may be introduced in a controllable manner into a thread trajectory previously formed in a vertebra such that threads are formed in the thread trajectory for subsequent insertion of a pedicle screw.

[0076] 7 shows a thread passage forming instrument 99. It comprises an elongate shaft 92 and a tap or thread forming means 97 at one end. It further comprises an external threaded portion 62 having a larger diameter than the shaft 92, approximately midway along the longitudinal length of the instrument. It further comprises a guide tool mating section 98 between the external threaded portion 62 and the thread forming means 97, which takes the form of a cylinder having a larger diameter than the shaft 92. It further comprises a collar 91 at the end distal from the thread forming means 97, having a larger diameter than the shaft 92.

[0077] In use, the thread trajectory forming instrument 99 may be inserted into the aperture 33 of the thread trajectory forming instrument receiving member 30. The guide tool mating section 98 passes tightly through the thread trajectory forming instrument receiving section of the guide tool 60 so that the alignment of the instrument is controlled. The instrument may then be rotated by hand so that the external threads cooperate with the threads 34 provided in the bore of the thread trajectory forming instrument receiving member 30. In this manner, the thread forming means 97 may be introduced in a controllable manner into a thread trajectory previously formed in the vertebra, creating threads in the thread trajectory for subsequent insertion of the pedicle screw. The thread trajectory may be considered to be the thread trajectory at this stage.

[0078] The collar 91 prevents over-insertion of the instrument into the vertebrae.

[0079] The instrument 99 and guide tool 60 may then be removed so that the guide tool stem is removed from the guide tool stem receiving section 24 of the pedicle screw 20 in the vertebra below the one in which the screw pathway was just created.

[0080] In an alternative method shown in FIG. 6 a, where the screw path forming instrument receiving member 30 is attached to the connector 100, the instrument 99 and screw path forming instrument receiving member 30 can then be removed so that the connector 100 remains in place with the connector stem 110 inserted into the connector stem receiving section 24 of the pedicle screw 20 in the vertebra below the one in which the screw path was just formed.

[0081] 8, the selection of the guide tool 60 not only improves the placement of the pedicle screw, but the guide tool stem receiving section 24 in each pedicle screw 20 includes a guide tool stem receiving section that is a bore 24 through a spherical portion 26 that fits between the arms of the guide tool stem receiving section 24 and is rotatable relative thereto as a ball and socket joint or joint. In this manner, with the guide tool stem 80 inserted into the guide tool stem receiving section 24, the guide tool 60 is movable relative to the long axis of the threaded stem 22 of the pedicle screw 20. This movement is limited by the stem 80 contacting the arms of the guide tool stem receiving section 24, but still allows a significant amount of movement so that the thread trajectory forming instrument receiving section 70 of the guide tool can be positioned as needed.

[0082] FIG. 9 shows the guide tool stem receiving section 24 in two different positions relative to the arms of the guide tool stem receiving section 24 to illustrate this relative movement.

[0083] With the selection of the appropriate guide tool 60, along with the location and orientation of the selected screw trajectory forming instrument receiving section 70 and the orientation of the ball portion 26, and thus the guide tool relative to the long axis of the threaded stem 22 of the pedicle screw in the adjacent vertebra, the surgeon may now create a screw trajectory in the vertebra with the drilling tool. In this regard, the ball portion 26 may be positioned so that it does not move freely within the arms of the guide tool stem receiving section 24 so that the act of inserting a drilling tool through the trajectory portion 70 would move the ball portion 26, but it may move sufficiently so that it can be moved by hand.

[0084] After removal of the guide tool stem from the connector stem receiving section 24 in the inferior pedicle screw, a connector stem 110 may then alternatively be inserted into the connector stem receiving section 24. The connector 100 may be selected from a range of connectors, as shown in FIG. 10, that have the same or very similar shape (length, angle of stem 110 extending from head 120, etc.) as the aforementioned range of guide tools 60. It is envisioned that the surgeon will select a connector that has the same shape as the guide tool 60 used to form the screw trajectory, but this is not necessarily the case.

[0085] As shown in FIG. 11, the head 120 of each connector 100 in the range includes a pedicle screw receiving section 130 that includes an aperture 135. The stem 110 is inserted into the connector stem receiving section 24 of the pedicle screw in the vertebra below the one in which the screw channel has just been created. Although the aperture 135 is shown as a circular screw channel configured to receive the pedicle screw, other shapes that allow the pedicle screw to be fitted are envisioned. Thus, the new pedicle screw 20 is inserted through this aperture 135 into the already created screw channel.

[0086] Because the selected connector 100 has the same geometry (shape, configuration, length, angle, etc.) as the guide tool 60 used with the drilling tool 90 to form the screw path, it is envisioned that the new pedicle screw 20 will be smoothly and relatively easily inserted into the vertebra and positioned in the selected orientation relative thereto.

[0087] The stem 110 of the connector 100 is shown in Fig. 12 inserted into the connector stem receiving section 24 of the pedicle screw 20. The stem 100 passes through the guide tool stem receiving section 24 (which at this stage functions as the connector stem receiving section 24) constituted by a ball-shaped portion 26 disposed within the arm of the connector stem receiving section 24. However, it will be appreciated that with the connector stem 110 of the connector 100 in place in the connector stem receiving section 24, and with a new pedicle screw inserted through the pedicle screw receiving section 130 of the same connector 100, the ball joint does not move freely as it did before the connector stem was inserted. Fig. 14 shows the connector 100 with a pedicle screw 20 inserted through the opening 135.

[0088] The above method can be repeated for additional vertebrae as necessary so that several vertebrae, each with a pedicle screw inserted, are connected together using connectors as shown in FIG. 1.

[0089] The spinal fastening element system 5 can then be used to correct spinal deformities. This can be achieved by each connector 100 allowing movement of the pedicle screw 20 through its pedicle screw receiving section 130 relative to its stem 110. This can be achieved by configuring the pedicle screw receiving section 130 to pivot or rotate within arms 140 located on either side of the head 120. In FIG. 13 it can be seen that the pedicle screw receiving section 130 includes a projection 145 with an arcuate surface corresponding to and slidable on the posterior arcuate surface 144 of the head 140 of the connector 100. These two opposing surfaces 144, 145 allow the pedicle screw receiving section 130 to move in a rotational manner about an axis extending laterally perpendicular to the longitudinal length of the stem 110 (i.e., an axis extending laterally generally parallel to the intersection of the coronal and transverse planes). However, rather than allowing this movement to be uncontrolled, a ratchet 150 is disposed between at least one of the two opposing outer surfaces of the pedicle screw receiving section 130 and at least one of the inner surfaces of the arms 140 of the head 140. The ratchet 150 may be a series of ridges provided on each of these two surfaces.

[0090] Thus, in use, the ratchet can be configured to allow two adjacent pedicle screws (each installed in adjacent vertebrae) to rotate about a common axis (generally parallel to the intersection of the coronal and transverse planes).

[0091] The ratchet 150 may allow the two pedicle screws to rotate only in substantially opposite rotational directions about this common axis, such that over a period of time and with active and passive movement of the spine during normal daily activities and exercise, gradual correction of the spinal deformity may be achieved by only allowing the leading edges of the end plates of two substantially adjacent vertebrae to move substantially closer to each other or further away from each other.

[0092] 11 shows a line 113 extending along the stem 110 of the connector 100 from the head 120 generally, but not entirely, to the very end of the stem distal to the head 120. This line shows how the arms 120 of the stem 110 and head 140 are split in two so that they can be pulled apart slightly. This allows the pedicle screw receiving section 130 to be rotated within the arms 140 without the ratchet 150 engaged, allowing the pedicle screw receiving section 130 to be oriented as needed relative to the longitudinal length of the stem 110 prior to insertion of the stem 110 into the connector stem receiving section 24 of a pedicle screw installed in an adjacent vertebra.

Claims

1. 1. A spinal fastening element system comprising a guide tool for aligning a screw trajectory formation instrument for use in forming a screw trajectory in a vertebra for subsequent placement of a pedicle screw, said guide tool comprising a guide tool stem and a screw trajectory formation instrument receiving section, said guide tool stem and said screw trajectory formation instrument receiving section being immobile relative to one another; Spinal fastening element system.

2. the guide tool comprises a substantially radiolucent material; The spinal fastening element system of claim 1 .

3. the thread path forming instrument receiving section includes a path portion open at both axial ends, the path portion including a bore, the bore having a longitudinal axis; The spinal fastening element system according to any one of claims 1 and 2.

4. the passageway being defined by a cylindrical wall, the cylindrical wall including a slot that, in use, allows a guidewire to be inserted into the passageway. The spinal fastening element system of claim 3 .

5. the guide tool stem is configured to mate with a guide tool stem receiving section of an adjacent pedicle screw in use; The spinal fastening element system according to any one of claims 1 to 4.

6. the spinal fastening element system further comprising a thread path forming instrument for use in forming a thread path in a vertebra for subsequent placement of a pedicle screw, the thread path forming instrument including a guide tool mating section for aligning the thread path forming instrument relative to the guide tool; The spinal fastening element system according to any one of claims 1 to 5.

7. the spinal fastening element system further comprising a thread trajectory forming instrument receiving member, the thread trajectory forming instrument receiving member including an attachment means for attaching the thread trajectory forming instrument receiving member to the guide tool, the thread trajectory forming instrument receiving member including an internal thread for receiving a thread trajectory forming instrument for creating a thread on an internal surface of the thread trajectory created in the vertebra by the thread trajectory forming instrument; The spinal fastening element system of claim 6.

8. and a thread trajectory forming instrument having an external thread for reception in the thread trajectory forming instrument receiving member and for creating the threads on an internal surface of the thread trajectory created in the vertebra by the thread trajectory forming instrument. The spinal fastening element system of claim 7.

9. the thread path forming instrument including a guide tool mating section for aligning the thread path forming instrument with respect to the guide tool; The spinal fastening element system of claim 8.

10. the guide tool mating section having a size and shape that closely matches the size and shape of the aperture in the passageway such that the guide tool mating section is receivable in use within the aperture in the passageway to thereby align the thread passageway forming instrument. The spinal fastening element system according to claim 9 when dependent on claim 3.

11. the guide tool mating section including a depth limiter for limiting axial movement of the thread path forming instrument in one direction parallel to the longitudinal axis of the bore of the channel along the longitudinal axis when the thread path forming instrument is received in the thread path forming instrument receiving section. The thread path forming instrument of claim 10.

12. the spinal fastening element system further comprising a pedicle screw, the pedicle screw comprising a guide tool stem receiving section for receiving, in use, the guide tool stem of an adjacent guide tool; The spinal fastening element system according to any one of claims 1 to 11.

13. the pedicle screw comprises a threaded shaft, and the guide tool stem receiving section of the pedicle screw comprises a ball joint for articulation of the guide tool stem relative to the shaft. The spinal fastening element system of claim 12.

14. the spinal fastening element system further comprising a connector, the connector comprising a connector stem and a pedicle screw receiving section, the pedicle screw receiving section for receiving the guide tool stem receiving section of the pedicle screw in use; The spinal fastening element system according to any one of claims 12 and 13.

15. the connector further comprising a ratchet for controlling movement of the pedicle screw receiving section relative to the connector stem. The spinal fastening element system of claim 14.

16. the connector stem having substantially the same shape and size as the guide tool stem; The spinal fastening element system according to any one of claims 14 and 15.

17. 1. A method of installing a second pedicle screw in a second vertebra adjacent to a first vertebra, the first vertebra including a previously installed first pedicle screw, the method comprising: a) providing a guide tool according to any one of claims 1 to 16; b) inserting the guide tool stem into a guide tool stem receiving section of the first pedicle screw pre-installed in the first vertebra; c) positioning the screw path formation instrument receiving section at a selected location relative to the second vertebra; d) inserting the thread path forming instrument into the thread path forming instrument receiving section; e) creating an initial hole in the second vertebra by operating the screw path preparation instrument; f) removing the thread path preparation instrument from the guide tool; g) mounting a thread path forming instrument receiving member onto the guide tool; h) inserting said thread path forming instrument into said thread path forming instrument receiving section; i) operating the screw path forming instrument to create a screw path with threads on an internal side of the screw path created in the second vertebra; j) removing the thread path forming instrument from the thread path forming instrument receiving member; k) removing the guide tool stem from the guide tool stem receiving section of the first pedicle screw pre-installed in the first vertebra; l) replacing the guide tool with a connector, the connector including a connector stem and a pedicle screw receiving section; m) inserting the second pedicle screw into the pedicle screw receiving section of the connector and into the threaded screw passage formed in the second vertebra; A method of installing a second pedicle screw, comprising:

18. the connector in step l) is selected from a range of connectors each having a different connector stem length such that the selected connector has the same stem length as the selected guide tool stem length; 20. The method of installing a second pedicle screw according to claim 17.

19. 1. A method of installing a second pedicle screw in a second vertebra adjacent to a first vertebra, the first vertebra including a previously installed first pedicle screw, the method comprising: a) providing a guide tool according to any one of claims 1 to 16; b) inserting the guide tool stem into a guide tool stem receiving section of the first pedicle screw pre-installed in the first vertebra; c) positioning the screw path formation instrument receiving section at a selected location relative to the second vertebra; d) inserting the thread path forming instrument into the thread path forming instrument receiving section; e) creating an initial hole in the second vertebra by operating the screw path preparation instrument; f) removing the thread path preparation instrument from the guide tool; g) removing the guide tool stem from the guide tool stem receiving section of the first pedicle screw pre-installed in the first vertebra; h) attaching a screw trajectory forming instrument receiving member to a connector, said connector including a connector stem and a pedicle screw receiving section; i) inserting the connector stem into a guide tool receiving section of the first pedicle screw pre-installed in the first vertebra; j) inserting the thread path forming instrument into the thread path forming instrument receiving section; k) operating the screw path forming instrument to create a screw path with threads on the inside of the screw path created in the second vertebra; l) removing the thread path forming instrument from the thread path forming instrument receiving member; and m) removing the thread path forming member from the connector; n) inserting the second pedicle screw into the pedicle screw receiving section of the connector and into the threaded screw passage formed in the second vertebra; A method of installing a second pedicle screw, comprising:

20. The guide tool in step a) is selected from a range of guide tools each having a different stem length.

20. A method of installing a second pedicle screw according to any one of claims 17 and 19.

21. The connector in step h) is selected from a range of connectors each having a different connector stem length such that the selected connector has the same stem length as the selected guide tool stem length.

20. The method of installing a second pedicle screw according to claim 19.

Images