Spinal support 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 generally relates to spinal fixation element systems, and methods for installing pedicle screws, and demonstrates particular utility in spinal deformity correction surgery through the use of surgically implantable devices, although not limited thereto.

Background Art

[0002] Currently, spinal fixation elements, such as pedicle screws, are surgically inserted into the posterior elements (pedicles) of the spine as a means of mechanical support for 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] First, a plurality of pedicle screws are inserted into various vertebrae of the spine, and subsequently, these pedicle screws can be connected to each other. Such a connection between two or more implanted pedicle screws can be achieved by a fixed method that prevents movement between the connected pedicle screws, or by a movable method that allows various desired degrees of movement between the connected pedicle screws. An example of a connection by a fixed method is described in U.S. Patent No. 2011034258(A1), which discloses a method for attaching the head of a pedicle screw to a bone fixation device component to fix the bone fixation device component to bone by a multi-axis method. When such a connection between two or more implanted pedicle screws is achieved by a fixed method, the pedicle screws can be connected together by, for example, a rod-type connector disclosed in U.S. Patent No. 2006036242(A1). When the connector is of the rod type, it is known that the surgeon usually needs to bend the rod connector by various methods during surgery to achieve a connector shape suitable for connecting two or more pedicle screws arranged at various positions along the spine.

[0004] However, the connector may be of a more complex type than a rod, and such a connector may not need to be adapted to bending 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 method that allows for various desirable degrees of movement between the connected pedicle screws. An example of a movable connection method is described, for example, in the case of artificial interspinal joint prostheses, as described in U.S. Patent No. 20060265074(A1).

[0005] Conventional devices for correcting spinal deformities involve the fixation of bone screws connected to a rod via a pivoting connection, as described, for example, in WO2007014119A2. Furthermore, the use of ratchet mechanisms in conjunction with spinal implants is known from WO2010067113A1 and U.S. Patent No. 2016338738(A1).

[0006] U.S. Patent No. 2016338738(A1) describes a connector used to connect individual pedicle screws together, which can 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 the 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 have a ball joint that allows for limited articular movement of the connector stem relative to the shaft of the pedicle screw.

[0008] This method enables relative movement between a series of pedicle screws and connectors, thus providing an environment in which spinal deformities can be corrected over time.

[0009] To use a connector to connect two adjacent pedicle screws, the screws must be positioned in a specific location, because otherwise the connector may not fit correctly between them. This means that during surgery, the placement of pedicle screws is limited to a specific range of positions relative to adjacent pedicle screws. If adjacent pedicle screws are positioned in a location where a connector cannot be used to connect them together, or in a position that does not provide the required range of motion for the spine when they are connected to each other, the pedicle screws will need to be moved. This is, of course, undesirable. Rather, it is important to position the pedicle screws in their correct locations on the first attempt.

[0010] Furthermore, typically, after pathways have been formed in the vertebra, pedicle screws are installed. These pathways are created using tools such as screw pathway formation instruments, and then, after the pathways have formed, the tools are removed. If a connector is used that is connected to the first installed pedicle screw to guide the screw pathway formation instrument, the connector may be scratched or otherwise damaged. Using scratched or damaged connectors is undesirable because they can cause tissue damage after surgery. [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] Therefore, it is desirable to provide a tool that enables the correct and accurate positioning of pedicle screws during such surgery, in order to avoid misplacing the screws, to avoid the inability to connect the screws together later using connectors, and to avoid damage to the connectors. [Means for solving the problem]

[0012] In a first embodiment, the present invention provides a spinal retaining 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, wherein the guide tool comprises a guide tool stem and a screw path forming instrument receiving section, and the guide tool stem and the screw path forming instrument receiving section are not movable relative to each other.

[0013] During use, after the first pedicle screw is placed in the vertebra, the guide tool can be connected to the first pedicle screw by inserting the guide tool stem into the guide tool stem receiving section of the pedicle screw. The thread path formation device receiving section can then be used to receive one or more thread path formation devices to create thread paths in adjacent vertebrae. Next, the thread path formation devices can be removed. Then, the guide tool can be removed. Next, the second pedicle screw can be placed in the thread path using connectors connected to the first and second pedicle screws.

[0014] The guide tool may contain substantially radiolucent material. This is so that the (non-radiolucent) thread path formation tool is not obscured by the guide tool during surgery, allowing the precise location and orientation of the thread path for the screw to be optimally selected using radiography.

[0015] In contrast, if a non-radioactive connector is used during surgery instead of a guide tool to function as a guide for preparing the thread path for a screw, the non-radioactive connector can obscure the radiographic image of the spinal elements. This poses a risk that the thread path for the screw may not be formed in the optimal position and / or with the optimal orientation. This can result in damage to important spinal structures, such as nerves or the spinal cord. This problem can be avoided if the guide tool is radiolucent.

[0016] The thread path forming tool receiving section may have a path portion open at both axial ends, the path portion including a hole, the hole having a long axis.

[0017] The pathway may be defined by a cylindrical wall, which may include a slot that allows a guidewire to be inserted into the pathway during use. The guidewire may be used for positioning pedicle screws. The guide tool stem may be configured to fit into the guide tool stem receiving section of an adjacent pedicle screw during use.

[0018] The spinal retaining element system may further comprise a thread path forming instrument for use in forming thread paths in the vertebrae for subsequent installation of pedicle screws. For example, a piton may be used to create an initial indentation or hole in the bone. The piton may then be replaced with a pedicle finder, and both of these may be understood as thread path or hole forming instruments.

[0019] The thread path forming device may include a fitting section that is sized and shaped to closely match the size and shape of the hole in the path (the thread path forming device receiving section), so that the fitting section can be received into the hole in the path when in use, thereby aligning the thread path forming device.

[0020] The thread path forming tool may include a depth limiter for restricting axial movement of the thread path forming tool in one direction parallel to the major axis of the hole in the path along the major axis, while the thread path forming tool is received in the thread path forming tool receiving section. The depth limiter may be a collar positioned on the stem of the thread path forming tool.

[0021] After the pedicle finder is used to generate an initial path for the placement of the pedicle screw, it can be removed from the guiding tool.

[0022] The spinal fixation element system may further include a screw path forming tool receiving member, the screw path forming tool receiving member including attachment means for attaching it to a guide tool, the screw path forming tool receiving member having an internal thread for receiving, with rotation, a screw path forming tool for generating a thread on the inner surface of a screw path generated in a vertebra by the screw path forming tool.

[0023] The attachment means may be a clamping mechanism for clamping the screw path forming tool receiving member to the guide tool.

[0024] The spinal fixation element system may further include a screw path forming tool having an external thread for receiving, with rotation, the screw path forming tool receiving member and for generating a thread on the inner surface of a screw path generated in a vertebra by the screw path forming tool.

[0025] The screw path forming tool may include a guide tool fitting section for aligning the screw path forming tool with respect to the guide tool.

[0026] By being able to be received in a hole in the path portion during use, the guide tool fitting section may have a size and shape that closely match the size and shape of the hole in the path portion in order to align the screw path forming tool.

[0027] During use, the screw path forming tool may be inserted into an opening at the axial end of the screw path forming tool receiving member distal from the guide tool and then rotated, by interaction of the threads, to move into a previously generated screw path in the vertebra so as to generate a thread on the inner surface of the screw path. In this regard, the screw path forming tool may be considered a tap. The amount of insertion depth of the screw path forming tool into the vertebra may be controlled by the rotational movement of the screw path forming tool with respect to the screw path forming tool receiving member.

[0028] The guide tool mating section may include a depth limiting portion for restricting the axial movement of the screw path forming instrument in one direction parallel to the long axis of the hole in the path portion along the long axis, with the screw path forming instrument received in the screw path forming instrument receiving section of the guide tool. The depth limiting portion may be a collar in the stem of the screw path forming instrument having a radius larger than the hole in the path portion so that it cannot enter the path portion.

[0029] The spinal fixation element system may further include pedicle screws, and the pedicle screws include a guide tool stem receiving section for receiving the guide tool stem of an adjacent guide tool during use. Note that the guide tool stem receiving section may also be known as a connector stem receiving section since it can be used to receive a connector stem after the guide tool is removed.

[0030] The spinal fixation element system may further include a connector, and the connector includes a connector stem and a pedicle screw receiving section, and the pedicle screw receiving section is for receiving the guide tool stem receiving section of the pedicle screw during use. The connector stem and the pedicle screw receiving section may be movable relative to each other about an axis parallel to the intersection of the coronal plane and the transverse plane during use.

[0031] During 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 include a ratchet for controlling the movement of the pedicle screw receiving section relative to the connector stem about an axis parallel to the intersection of the coronal plane and the transverse plane during use.

[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. Furthermore, the connector may be selected from a range of connectors, each having a different connector stem length. A connector within a range of connectors may include a connector stem having a shape and size equivalent to a guide tool stem within a range of guide tools. The shape and size may be identical. This method allows the surgeon to select a guide tool containing the most appropriate shape and size guide tool stem to ensure correct connection between adjacent pedicle screws, then use the selected guide tool to create a path for the second pedicle screw, and finally replace the selected guide tool with an equivalent connector.

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

[0035] In a second embodiment, the present invention relates to a method for installing a second pedicle screw in a second vertebra adjacent to a first vertebra, wherein the first vertebra includes a pre-installed first pedicle screw, and the method is a) A step of providing a guide tool according to the first embodiment, b) The step of inserting the guide tool stem into the guide tool stem receiving section of the first pedicle screw that has been pre-installed in the first vertebra, c) The step of positioning the screw pathway forming device receiving section at a selected position relative to the second vertebra, d) The step of inserting a thread path forming tool into the thread path forming tool receiving section, e) The step of creating an initial hole in the second vertebra by operating a screw path forming device, f) The step of removing the thread path forming tool from the guide tool, g) A step of attaching a thread path forming tool receiving member to the guide tool, h) The step of inserting another thread path forming tool into the thread path forming tool receiving section, i) A step of operating a thread path forming device to create a thread path having threads inside the thread path formed in the second vertebra, j) The step of removing the thread path forming tool from the thread path forming tool receiving member, k) The step of removing the guide tool stem from the guide tool stem receiving section of the first pedicle screw that has been pre-installed in the first vertebra, l) A step of replacing a guide tool with a connector, wherein the connector includes a connector stem and a pedicle screw receiving section. m) The step of inserting a second pedicle screw into the pedicle screw receiving section of the connector and into the threaded screw path formed in the second vertebra, This may provide a method that includes [this].

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

[0037] In a third embodiment, the present invention relates to a method for installing a second pedicle screw in a second vertebra adjacent to a first vertebra, wherein the first vertebra includes a pre-installed first pedicle screw, and the method is a) A step of providing a guide tool according to the first embodiment, b) The step of inserting the guide tool stem into the guide tool stem receiving section of the first pedicle screw that has been pre-installed in the first vertebra, c) The step of positioning the screw pathway forming device receiving section at a selected position relative to the second vertebra, d) The step of inserting a thread path forming tool into the thread path forming tool receiving section, e) The step of creating an initial hole in the second vertebra by operating a screw path forming device, f) The step of removing the thread path forming tool from the guide tool, g) The step of removing the guide tool stem from the guide tool stem receiving section of the first pedicle screw that has been pre-installed in the first vertebra, h) A step of attaching a thread path forming device receiving member to a connector, wherein the connector includes a connector stem and a pedicle thread receiving section; i) Inserting the connector stem into the guide tool receiving section of the first pedicle screw that has been pre-installed in the first vertebra, j) The step of inserting the thread path forming tool into the thread path forming tool receiving section, k) A step of operating a thread path forming device to create a thread path having threads inside the thread path formed in the second vertebra, l) The step of removing the thread path forming tool from the thread path forming tool receiving member, m) The step of removing the thread path forming member from the connector, n) The step of inserting a second pedicle screw into the pedicle screw receiving section of the connector and into the threaded screw path formed in the second vertebra, This may provide a method that includes [this].

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

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

[0040] Because the thread path forming member is firmly attached to the connector, there is no possibility of the connector being damaged by the thread path forming tool.

[0041] In any of the methods for installing 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] In step h) of the third embodiment, the connector may be selected from a range of connectors, each having different connector stem lengths, such that the selected connector has the same stem length as the selected guide tool stem length.

[0043] The above-mentioned 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 illustrating the principles of the present invention. This description is provided for illustrative purposes only and is not intended to limit the scope of the present invention. Reference drawings cited below represent the accompanying drawings. [Brief explanation of the drawing]

[0044] [Figure 1] Figure 1 is a perspective view of three adjacent vertebrae, including a spinal alignment device. [Figure 2] Figure 2 is a perspective view of two adjacent vertebrae, including pedicle screws and corresponding guide tools. [Figure 3] Figure 3 is a perspective view of guide tools of different sizes within a certain range. [Figure 4] Figure 4 shows two perspective views of the guide tool. [Figure 5] Figure 5 is a perspective view of the thread path forming tool and guide tool. [Figure 6] Figure 6 is a perspective view of the thread path forming tool receiving section and the guide tool mounted together. [Figure 6a] Figure 6a is a cross-sectional view of the thread path forming device receiving section and the connector fitted together. [Figure 6b]Figure 6b is a perspective view of the thread path forming tool receiving section with a portion of the thread path forming tool inserted. [Figure 7] Figure 7 is a perspective view of a thread path forming device. [Figure 8] Figure 8 shows two perspective views of the pedicle screw. [Figure 9] Figure 9 shows two perspective views of a portion of a pedicle screw. [Figure 10] Figure 10 is a perspective view of connectors of different sizes within a certain range. [Figure 11] Figure 11 shows two perspective views of the connector. [Figure 12] Figure 12 is a perspective view of the pedicle screw and connector. [Figure 13] Figure 13 shows two perspective views of the connector. [Figure 14] Figure 14 is a perspective view of the connector and pedicle screw. [Modes for carrying out the invention]

[0045] The present invention is described in relation to specific drawings, but is not limited thereto, and is limited only by the claims. The drawings described are schematic and not limiting. Each drawing may not contain all of the features of the present invention and therefore cannot necessarily be considered an embodiment of the present invention. Some sizes of elements in the drawings may be exaggerated for illustrative purposes and may not be drawn to a certain scale. Dimensions and relative dimensions do not correspond to actual scaled-down versions of the embodiment of the present invention.

[0046] Furthermore, terms such as "first," "second," and "third" in this description and claims are used to distinguish similar elements and are not necessarily used to describe order in time, space, sequence, or any other way. It is understood that terms used in this way are interchangeable with one another in appropriate contexts and that they may operate in a different order than those described or illustrated herein. Similarly, method steps described in a particular order or described in a claim may be understood to operate in a different order.

[0047] Furthermore, terms such as top, bottom, above, and below in this description and claims are used for descriptive purposes only and are not necessarily used to describe relative positions. It should be understood that terms used in this way are interchangeable with each other in appropriate contexts and that operation is possible in orientations other than those described or illustrated further herein.

[0048] The expression “equipped with” (including, having, possessing) as used in the claims should not be construed as limiting to the means listed thereafter, and it should be noted that these expressions do not exclude other elements and steps. Therefore, it is construed as specifying the presence of the described features, integers, steps, or components as mentioned, but does not exclude the presence or addition of one or more other features, integers, steps, or components, or groups thereof. Accordingly, the scope of the expression “a device comprising means A and B” should not be limited to a device consisting solely of components A and B. In relation to the present invention, it simply means that the relevant components of the device are A and B.

[0049] Any reference to “embodiments” or “aspects” in this specification means that any particular feature, structure, or characteristic described in relation to an embodiment or aspect is included in at least one embodiment or aspect of the present invention. Therefore, the use of the expressions “in one embodiment,” “in an embodiment,” or “in a aspect” in various places in this specification may not all relate to the same embodiment or aspect, but may represent different embodiments or aspects. Furthermore, any particular feature, structure, or characteristic of any one embodiment or aspect of the present invention may be combined in any appropriate manner with any other particular feature, structure, or characteristic of another embodiment or aspect of the present invention, as will be apparent to those skilled in the art from this disclosure, in one or more embodiments or aspects.

[0050] Similarly, it should be understood that in this description, various features of the present invention may be grouped together in a single embodiment, figure, or description thereof for the purpose of simplifying this disclosure and aiding in the understanding of one or more of the various embodiments of the invention. However, this method of disclosure is not to be interpreted as reflecting an intention that the invention described in the claims requires more features than those explicitly described in each claim. Furthermore, not any individual drawing or description of an embodiment of the present invention is necessarily considered to be an embodiment of the present invention. Rather, as the claims described below demonstrate, embodiments of the invention reside in fewer features than all the features of one of the aforementioned disclosed embodiments. Accordingly, the claims following the detailed description are explicitly incorporated herein into this detailed description, and each claim is independent as a separate embodiment of the present invention.

[0051] Furthermore, while some embodiments described herein include some features included in other embodiments, combinations of features from different embodiments are intended to be within the scope of the invention so as will be understood by those skilled in the art, forming yet another set of embodiments. For example, in the claims described below, any embodiment among those described in the claims may be used in any combination.

[0052] Many specific details are described in the description provided herein. However, it should be understood that embodiments of the present invention may be carried out without these specific details. In other examples, well-known methods, structures, and techniques are not shown in detail so as not to hinder the understanding of this description.

[0053] In the discussion of the present invention, unless otherwise stated, the disclosure of alternative values ​​for an upper or lower limit of an acceptable range of parameters, linked to the indication that one of the values ​​is much more preferable than the others, is interpreted as an implicit statement that each of the values ​​between the preferred value and the less preferred value of the alternative is preferable to the less preferred value, and to each of the values ​​between the less preferred value and the values ​​in between.

[0054] The use of the term "at least one" can mean exactly one in certain contexts. The use of the term "any" can mean "all" and / or "each" in certain contexts.

[0055] The principles of the present invention are described below with reference to a detailed description of at least one drawing relating to exemplary features. It will be apparent that other configurations can be constructed based on the knowledge of those skilled in the art without departing from the underlying concepts or technical teachings, and the present invention is limited only by the language of the appended claims.

[0056] Figure 1 shows three adjacent vertebrae 10a, 10b, and 10c together with the attached spinal retaining element system 5. This device comprises pedicle screws 20a, 20b, and 20c, with each vertebra containing one screw inserted into its posterior element (pedicle). Each pedicle screw includes connector stem receiving sections 24a, 24b, and 24c. The uppermost pedicle screw 10c is inserted through connector 100. Connector 100 comprises a head 120 and a stem 110 extending therefrom. The uppermost pedicle screw 10c is inserted through the head 120 of the uppermost connector 100. The stem 110 of the uppermost connector extends downward and through the connector stem receiving section 24b of the central pedicle screw 20b. Similarly, the central pedicle screw 10b is inserted through connector 100. The central connector stem 110 extends downward and through the connector stem receiving section 24a of the lowest pedicle thread 20a. The connector stem receiving section may be a socket.

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

[0058] Figure 2 shows two adjacent vertebrae 10a and 10b. 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, initially, a guide tool 60 is used in place of the 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 called the guide tool stem receiving section 24 when it is used for the purpose of the guide tool stem receiving section, and the connector stem receiving section 24 when it is used for the purpose of the connector stem receiving section.

[0059] With the stem 80 received in the guide tool stem receiving section 24, the head 65 is positioned adjacent to the uppermost vertebra 10b. The guide tool 60 further comprises a pathway in the head 65 defined by a cylindrical wall (screw pathway 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 part of the vertebra.

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

[0061] The present invention was conceived due to the need to correct spinal misalignment over time. As described above, in order to use a connector to connect two adjacent pedicle screws, the screws must be placed in specific positions, because otherwise the connector may not fit properly between them. This means that during surgery, the placement of pedicle screws is limited to a certain number of positions within a specific range relative to adjacent pedicle screws. If 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 restriction of movement on the spine when they are connected to each other, the pedicle screws will need to be moved. This is, of course, undesirable. Rather, it is important to place the pedicle screws in the correct position on the first attempt.

[0062] Therefore, it is desirable to provide a tool that enables the correct and accurate positioning of pedicle screws during such surgery, in order to avoid misplacement of screws, to avoid the inability to connect the screws together later using connectors, and to avoid damage to the connectors.

[0063] This is achieved by using a guide tool 60 that provides a pathway or a screw pathway receiving section 70 for receiving one or more screw pathway forming tools (drilling tools) for creating a pathway for receiving the next pedicle screw. When used, the surgeon can select which guide tool 60 to use from a range of guide tools shown in Figure 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 differ for each of the guide tools in that range. This method allows the surgeon to select the optimal guide tool from the range to ensure that the screw pathway receiving section 70 of the selected guide tool is adjacent to the portion of the vertebra where the next pedicle screw will be installed, and that the long axis of its hole is positioned at an optimal angle to the vertebra so that the pedicle screw 20 can be installed with the long axis of its threads 22 positioned at an appropriate angle to the vertebra.

[0064] Figure 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 upper surface of the cylindrical thread path forming instrument receiving section 70. When in use, this slot 82 allows a guide wire to be inserted into the path section 70. Such a guide wire can pass through and along the central hole of the pedicle screw 20 when in use. Each stem 80 includes a step portion 81 which can be used to limit the insertion depth of the stem 80 into the guide tool stem receiving section of the pedicle screw and through the guide tool stem receiving section of the pedicle screw. This limitation is achieved by the step portion widening the top of the stem 80 over approximately half its length along its longitudinal direction between its distal end and the end near the head 65, resulting in it being too wide to fit through the guide tool stem receiving section 24 of the pedicle screw 20.

[0065] The threads 61 are visible on the inner surface of the path portion 70. They are optionally present. If present, they can work in conjunction with threads 62 which may optionally be provided on the outer surface of the shaft 92 of the thread path forming tool (tap) 99 (Figure 7) for controllable insertion of the tool 99 into the bone (by its relative rotation) and removal from the bone.

[0066] An example of the thread path forming tool 90 is shown in Figure 5, which can be seen to include a long shaft 92, with a handle 94 at one end and a relatively pointed point 96 in the form of a tap at the opposite end. A guide tool fitting section 98, which is a cylindrical portion having substantially the same outer diameter as the inner diameter of the thread path forming tool receiving section 70 in the guide tool 60, is positioned on the shaft.

[0067] The tool 90 is shown in combination with the guide tool 60, with the shaft 92 inserted through the pathway (screw path formation instrument receiving section) 70. Since the diameter of the guide tool fitting section 98 is substantially the same as the inner diameter of the pathway of the screw path formation instrument receiving section 70, the long axis of the shaft 92 and the long axis of the pathway (screw path formation instrument receiving section) 70 of the guide tool 60 are coaxial. This allows the surgeon to stably create a screw path in the vertebra at the selected position and orientation, as determined by the selection of the guide tool and its position relative to the vertebra.

[0068] Step 91 is positioned at a certain length of the shaft 92 to prevent excessive insertion of the drill bit into the vertebral cavity and through the guide tool. The stepped change increases the diameter of the shaft so that its diameter is greater than the inner diameter of the screw path forming instrument receiving section 70, so that the shaft does not pass through the screw path forming instrument receiving section 70.

[0069] Various thread path formation tools (not all of which are shown) may be used in sequence via the thread path formation instrument receiving section 70 of the guide tool, for example, after a drill as described below, a pedicle finder may be used, and then a tap may be used. After the initial hole has been formed in the vertebra, the thread path formation tool may be removed from the guide tool 60.

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

[0071] In relation to Figure 6, the thread path forming tool receiving member 30 comprises a cylindrical body 31 containing a hole that extends along its entire length, such that it is hollow. One end of the hole is visible to the right of the body 31 in the form of an opening 33. The thread path forming tool receiving member 30 is shown mounted on the guide tool 60 at its left end 32. The wall of the hole has threads 34, as will be described later.

[0072] Figure 6a illustrates an alternative method in which the thread path forming device receiving member 30 is mounted on the connector 100 instead of the guide tool 60. The thread path forming device receiving member 30 includes an end cap 35 rotatably mounted on a body 31 via a coordinately operating thread 38. An internal member 36 is slidably positioned within a hole in the body 31. Rotation of the end cap 35 advances the internal member 36 toward the end 32 that is proximal to the vertebra when in use. This movement of the internal member can be used to clamp the head 120 of the connector 100 between the internal member and the proximal end 32.

[0073] The inner threads 34, which can engage with the threads 62 (Figure 7) of the thread path forming tool, are visible through the material.

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

[0075] During use, the thread path forming instrument 399 (only the lower half section is shown for clarity in the figure) can be inserted into the opening 333 of the thread path forming instrument receiving member 330. The instrument can then be rotated by hand so that the outer threads 362 of the thread path forming instrument 399 engage with and cooperate with the pin 337. This method allows the thread forming means to be introduced in a controllable manner into a previously formed thread path in the vertebra so that threads are formed in the thread path for subsequent insertion of a pedicle screw.

[0076] Figure 7 shows a thread path forming device 99. It comprises a long shaft 92 and a tap or thread forming means 97 at one end. It further comprises an outer threaded section 62 having a larger diameter than the shaft 92, located roughly in the middle along the longitudinal direction of the device. It further includes a guide tool fitting section 98, which takes the form of a cylinder having a larger diameter than the shaft 92, located between the outer threaded section 62 and the thread forming means 97. It further comprises a collar 91 having a larger diameter than the shaft 92 at the end distal to the thread forming means 97.

[0077] During use, the thread path forming instrument 99 can be inserted into the opening 33 of the thread path forming instrument receiving member 30. The guide tool fitting section 98 closely passes through the thread path forming instrument receiving section of the guide tool 60 so that the alignment of the instrument is controlled. The instrument can then be rotated by hand so that the outer thread engages with the thread 34 provided in the hole of the thread path forming instrument receiving member 30. In this manner, the thread forming means 97 can be introduced in a controllable manner into a previously formed thread path in the vertebra, generating threads in the thread path for subsequent insertion of a pedicle screw. The thread path can be considered to be a thread path at this stage.

[0078] Collar 91 prevents excessive insertion of instruments into the vertebral cavity.

[0079] Next, the instrument 99 and guide tool 60 may 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 vertebra in which the screw path has just been formed.

[0080] In the alternative method shown in Figure 6a, in which the thread path forming device receiving member 30 is attached to the connector 100, the device 99 and the thread path forming device 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 vertebrae below the vertebra in which the thread path has just been formed.

[0081] In relation to Figure 8, the selection of the guide tool 60 not only improves the placement of the pedicle screws, but the guide tool stem receiving section 24 in each pedicle screw 20 includes a guide tool stem receiving section which is a hole 24 through a spherical portion 26 that is fitted between the arms of the guide tool stem receiving section 24 and is rotatable relative to it as a ball joint or ball coupling. This method allows the guide tool 60 to move relative to the long axis of the threaded stem 22 of the pedicle screw 20 with the guide tool stem 80 inserted into the guide tool stem receiving section 24. This movement is limited by the stem 80 contacting the arms of the guide tool stem receiving section 24, but still allows for very large movements so that the thread path forming instrument receiving section 70 of the guide tool can be positioned as needed.

[0082] Figure 9 shows the guide tool stem receiving section 24 at two different positions relative to the arm to illustrate this relative movement.

[0083] By selecting an appropriate guide tool 60, the surgeon can create a threaded path in the vertebra at this stage with the drilling tool, depending on the position and orientation of the selected threaded path-forming instrument receiving section 70, the orientation of the spherical portion 26, and consequently, the orientation of the guide tool relative to the long axis of the threaded stem 22 of the pedicle screw in the adjacent vertebra. In this regard, the spherical portion 26 may be positioned so that it does not move freely within the arm of the guide tool stem receiving section 24 to the extent that the motion of inserting the drilling tool through the path section 70 moves the spherical portion 26. However, it can move sufficiently to be moved by hand.

[0084] After the guide tool stem is removed from the connector stem receiving section 24 in the inferior pedicle screw, the connector stem 110 may then be inserted into the connector stem receiving section 24 as an alternative. The connector 100 may be selected from a range of connectors, as shown in Figure 10. These connectors 100 have the same or very similar shape (length, angle of extension of the stem 110 from the head 120, etc.) as the guide tool 60 of the aforementioned range. It is assumed, but not necessarily, that the surgeon will select a connector with the same shape as the guide tool 60 used to form the screw path.

[0085] As shown in Figure 11, the head 120 of each connector 100 in that range includes a pedicle screw receiving section 130, which includes an opening 135. The stem 110 is inserted into the connector stem receiving section 24 of the pedicle screw in the vertebra below the vertebra where the screw path has just been formed. The opening 135 is shown as a circular screw path configured to receive the pedicle screw, but other shapes that would allow the pedicle screw to be fitted into are also conceivable. Thus, a new pedicle screw 20 is inserted through this opening 135 into the already formed screw path.

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

[0087] Figure 12 shows the stem 110 of connector 100 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 functions as the connector stem receiving section 24 at this stage), which is composed of a spherical portion 26 positioned within the arm of the connector stem receiving section 24. However, it is understood that with the connector stem 110 of 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 in the free state it was in before the connector stem was inserted. Figure 14 shows connector 100 with the pedicle screw 20 inserted through the opening 135.

[0088] The method described above can be repeated for further vertebrae as needed, so that several vertebrae are connected together using connectors, with each having a pedicle screw inserted, as shown in Figure 1.

[0089] Next, this spinal retaining element system 5 can be used to correct spinal deformities. This can be achieved by allowing each connector 100 to move a pedicle screw 20 through its pedicle screw receiving section 130 so as to move relative to its stem 110. This can be achieved by configuring the pedicle screw receiving section 130 to pivot or rotate within arms 140 positioned on either side of the head 120. In Figure 13, it can be seen that the pedicle screw receiving section 130 includes a projection 145 having an arched surface, corresponding to and slidable on the arched surface 144 at the rear of the head 140 of the connector 100. These two opposing surfaces 144, 145 allow the pedicle screw receiving section 130 to move by rotating around an axis extending laterally perpendicular to the longitudinal direction of the stem 110 (i.e., an axis extending laterally roughly parallel to the intersection of the coronal and transverse planes). However, rather than leaving this movement uncontrolled, the ratchet 150 is positioned between at least one of the two opposite outer surfaces of the pedicle screw receiving section 130 and at least one of the inner surfaces of the arm 140 of the head 140. The ratchet 150 may be a series of protrusions provided on each of these two surfaces.

[0090] Therefore, when in use, the ratchet may be configured to allow two adjacent pedicle screws (each mounted on an adjacent vertebra) to rotate around a common axis (generally parallel to the intersection of the coronal and transverse planes).

[0091] The ratchet 150 may allow two pedicle screws to rotate only in substantially opposite directions around this common axis, and as a result, progressive correction of spinal deformities may be achievable by allowing only movement over a period of time and through active and passive movements of the spine during normal daily activities and exercises, so as to move substantially so that the anterior edges of two substantially adjacent vertebral end plates move closer together or further apart from each other.

[0092] Note that in Figure 11, line 113 is shown to extend along the stem 110 of the connector 100 from the head 120, but not along the entire length, to the outermost end of the stem distal to the head 120. This line shows how the arm 120 of the stem 110 and head 140 is divided into two so that they can be slightly separated. This allows the pedicle screw receiving section 130 to be rotated within the arm 140 when the ratchet 150 is not engaged, and allows the pedicle screw receiving section 130 to be oriented as needed in the longitudinal direction of the stem 110 before insertion of the stem 110 into the connector stem receiving section 24 of the pedicle screw installed in the adjacent vertebra.

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