Bone anchor head converter

Abstract

To provide a pedicle screw tulip head converter.SOLUTION: A pedicle screw tulip head converter can have a first portion joined to a second portion. The first portion can have a surface parallel to a first portion plane, and an opening defining a first portion axis. The second portion can extend from the first portion and can have a surface parallel to a second portion plane, the second portion plane being perpendicular to the first portion plane. The second portion can have a curved surface that defines a second portion axis, the second portion axis being perpendicular to and coplanar with the first axis.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 62 / 828,827, filed April 3, 2019, and entitled “Bone Anchor Head Converter,” which is incorporated by reference in its entirety herein.

[0002] (background) Spinal fixation systems can be used to surgically fix, adjust, and / or align the spine. One type of spinal fixation system uses spinal fixation rods to support the spine and fix, adjust, align, and / or fuse all or a portion of the spine in a desired orientation. Attachment of the spinal fixation rods to the spine has been accomplished using a variety of vertebral anchors (i.e., bone anchors). Vertebral anchors include screws, hooks, pins, and bolts that are used to engage the vertebrae and connect the spinal rod to the vertebrae. Pedicle screws have been successfully used as vertebral anchors. Bone anchors (such as pedicle screws) and connectors can be combined with spinal rods to correct deformations of the natural spinal alignment as well as to repair trauma.

[0003] Generally, pedicle screws can have a head with a receiving opening in which a spinal rod can be secured. The open head of this type of pedicle screw is often referred to as a "tulip head." The open style tulip head pedicle screw allows a spinal fixation rod to be moved, or "secured," into the tulip head through the receiving opening after the pedicle screw is screwed into the pedicle bone. Once secured, a set screw can be threaded into the threads located inside the opening, effectively closing the opening and securing the spinal fixation rod to the pedicle screw.

[0004] Pedicle screw styles may also be "closed head" in which the head is not open to receive a rod that is moved or secured therein. Rather, the head of the screw has an opening or through-hole through which a spinal fixation rod may be fed and thereby secured to the pedicle screw. It is believed that closed head style pedicle screws can withstand greater forces exerted on the pedicle screw by a spinal fixation rod. For example, it is believed that closed head style pedicle screws can withstand greater forces exerted by a spinal fixation rod that may cause an open tulip style head to expand, thereby displacing the spinal fixation rod from its fixed position.

[0005] Sometimes a surgeon may wish to use a closed style pedicle screw when an open style tulip head has previously been set, i.e., screwed into a portion of the pedicle bone. During the course of spinal fixation, it may be discovered that the existing open style tulip head is undesirable, but removing it and replacing it with a closed style head would add to the operative time as well as cause additional trauma to the bone during the screw exchange process.

[0006] Thus, there remains an unmet need for devices, systems and methods that provide improved bone anchors. Summary of the Invention [Means for solving the problem]

[0007] (overview) A converter for a tulip head of a pedicle screw. The converter can couple a first portion to a second portion. The first portion can have a surface parallel to a first portion plane and an opening defining a first portion axis. The second portion can extend from the first portion and have a surface parallel to a second portion plane, the second portion plane being orthogonal to the first portion plane. The second portion can have a curved surface defining a second portion axis, the second portion axis being perpendicular to and coplanar with the first axis. (First aspect) a first portion and a second portion extending from the first portion; Equipped with the first portion has a surface parallel to a first portion plane and an opening defining a first portion axis perpendicular to the first portion plane; 1. A pedicle screw tulip head converter comprising: a first part having a surface parallel to a second part plane, the second part plane being perpendicular to the first part plane; and a second part having a shaped surface defining a second part axis, the second part axis being perpendicular to the first part axis and coplanar with the first part axis. (Second aspect) A pedicle screw tulip head converter according to the first aspect, characterized in that the shaped surface comprises a shaped surface of a partial cylinder. (Third aspect) 2. The pedicle screw tulip head converter according to claim 1, wherein the opening comprises an internal thread. (Fourth aspect) 2. The pedicle screw tulip head converter according to claim 1, wherein the second portion defines a second portion threaded opening. (Fifth aspect) 2. The pedicle screw tulip head converter of claim 1, wherein the second portion defines a second portion threaded opening including an internal thread and a second portion set screw threaded into the internal thread in a direction perpendicular to the first portion axis. (Sixth aspect) The pedicle screw tulip head converter according to the first aspect, characterized in that the shaped surface includes a shaped extension extending from the shaped surface a sufficient distance to form an included angle of at least 10 degrees to 90 degrees, measured from a plane in which the second part axis lies and which is perpendicular to the first part axis. (Seventh aspect) a first portion and a second portion extending from the first portion; Equipped with the first portion has a surface parallel to a first portion plane and a first portion opening defining a first portion axis perpendicular to the first portion plane; 1. A one-piece saddle-shaped pedicle screw tulip head converter, comprising: said second portion including at least one lobe extending downwardly from said first portion, said lobe having a surface parallel to a second portion plane, said second portion plane being perpendicular to said first portion plane, said lobe having a shaped surface defining a second portion axis, said second portion axis being perpendicular to and coplanar with said first portion axis. (Eighth aspect) 8. The pedicle screw tulip head converter according to claim 7, wherein the second portion includes a first lobe and a second lobe. (Ninth aspect) 8. The pedicle screw tulip head converter according to claim 7, wherein the second portion includes a first lobe and a second lobe, the first lobe and the second lobe being spaced apart and arranged parallel to each other. (Tenth aspect) 8. The pedicle screw tulip head converter according to claim 7, wherein the lobes include a closed periphery defining an enclosed opening. (Eleventh aspect) 8. The pedicle screw tulip head converter according to claim 7, wherein the second portion includes a first lobe and a second lobe, each of the first lobe and the second lobe including a closed periphery defining an enclosed opening. (12th aspect) 8. The pedicle screw tulip head converter according to claim 7, wherein the first portion opening includes an internal thread. (Thirteenth aspect) 1. A method for converting an open-style tulip head pedicle screw to a closed-style pedicle screw, comprising: providing an open style tulip head of a pedicle screw, the open style tulip head having an upper surface and a channel-like opening extending from the upper surface to a rod seating surface, the channel-like opening including internal threads for receiving a tulip head set screw along a tulip head set screw axis; Providing a converter member, said converter member comprising: a first portion and a second portion extending from the first portion; the first portion has a surface parallel to a first portion plane and a first portion opening defining a first portion axis perpendicular to the first portion plane; a step, the second portion having a surface parallel to a second part plane, the second part plane being perpendicular to the first part plane, the second portion having a contoured surface defining a second part axis, the second part axis being perpendicular to the first part axis and coplanar with the first part axis; coupling said converter member to said open style tulip head such that said first portion axis is aligned with said tulip head set screw axis; The method according to claim 1, further comprising: (14th aspect) 14. The method of claim 13, wherein the coupling step includes inserting the tulip head set screw through the first portion opening and threading the tulip head set screw into the internal threads. (Fifteenth aspect) 14. The method of claim 13, wherein the shaped surface comprises a part-cylindrical shaped surface. (16th aspect) 14. The method of claim 13, wherein the second portion defines a second portion threaded opening. (17th aspect) 14. The method of claim 13, wherein the second portion defines a second portion threaded opening including internal threads and a second portion set screw threaded into the internal threads in a direction perpendicular to the first portion axis. (Claim 18) 14. The method of claim 13, wherein the second portion includes a first lobe and a second lobe, the first lobe and the second lobe being spaced apart and disposed parallel. (19th aspect) 13. The method of claim 12, wherein the lobe includes a closed perimeter defining an enclosed opening. (20th aspect) 14. The method of claim 13, wherein the second portion comprises a first lobe and a second lobe, each of the first lobe and the second lobe comprising a closed perimeter defining an enclosed opening. [Brief description of the drawings]

[0008] BRIEF DESCRIPTION OF THE DRAWINGS The present disclosure will be more readily understood from the following detailed description of several exemplary embodiments in conjunction with the drawings, in which:

[0009] [Figure 1] FIG. 1 is a side elevation view of an exemplary open style tulip head pedicle screw.

[0010] [Diagram 2] FIG. 1 is a partial cross-sectional view of an exemplary open-style tulip-headed pedicle screw.

[0011] [Diagram 3] FIG. 1 is a schematic diagram of an example of an open-style tulip-headed pedicle screw attached to bone.

[0012] [Figure 4] FIG. 1 is a perspective view of an example of a closed-style pedicle screw of the present disclosure;

[0013] [Diagram 5] FIG. 1 is a partial perspective view of an example of an open style tulip head pedicle screw of the present disclosure;

[0014] [Figure 6] FIG. 2 is a perspective view of an example of a converter member of the present disclosure.

[0015] [Figure 7] FIG. 2 is a side view of an example converter member of the present disclosure.

[0016] [Figure 8] FIG. 2 is a perspective view of an example of a converter member of the present disclosure.

[0017] [Figure 9] FIG. 2 is a perspective view of an example of a converter member of the present disclosure.

[0018] [Figure 10] FIG. 2 is a perspective view of an example of a converter member of the present disclosure.

[0019] [Figure 11] FIG. 2 is a perspective view of an example of a converter member of the present disclosure.

[0020] [Figure 12] 12 is a cross-sectional view of section 12-12 of FIG. 11.

[0021] [Figure 13] FIG. 2 is a perspective view of an example of a converter member of the present disclosure.

[0022] [Figure 14] FIG. 1 is a flow chart diagram of an embodiment of a method for converting pedicle screws. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] (Detailed Description) Various non-limiting embodiments of the present disclosure are described below to provide a general understanding of the principles of structure, function, and use of the devices, systems, methods, and processes disclosed herein. One or more examples of these non-limiting embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the systems and methods specifically described herein and illustrated in the accompanying drawings are non-limiting embodiments. Features illustrated or described in connection with one non-limiting embodiment can be combined with features of other non-limiting embodiments. Such modifications and variations are intended to be included within the scope of the present disclosure.

[0024] Throughout this specification, references to "various embodiments," "some embodiments," "one embodiment," "some exemplary embodiments," "one exemplary embodiment," or "one embodiment" mean that a particular feature, structure, or characteristic described in connection with any embodiment is included in at least one embodiment. Thus, appearances of the phrases "in various embodiments," "in some embodiments," "in one embodiment," "in some exemplary embodiments," "in one exemplary embodiment," or "in one embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0025] The examples described herein are illustrative only and are provided to aid in the description of the apparatus, devices, systems, and methods described herein. None of the features or components shown in the figures or described below should be considered essential to any particular implementation of these apparatus, devices, systems, or methods, unless specifically specified as essential. For ease of reading and understanding, certain components, modules, or methods may only be described in conjunction with certain figures. Failure to specifically describe a combination or subcombination of components should not be understood to indicate that the combination or subcombination is not possible. In addition, with respect to a method described, whether or not the method is described in conjunction with a flow diagram, unless otherwise specified or required by the context, it should be understood that any explicit or implicit ordering of steps performed in the execution of the method does not imply that the steps must be performed in the order presented, but may instead be performed in a different order or in parallel.

[0026] Described herein are exemplary embodiments of bone anchors (e.g., anchors, screws, etc.) useful in orthopedic procedures such as, for example, spinal fixation. In the illustrated embodiment, a pedicle screw is disclosed to teach the features and advantages of bone screws, but the disclosure is not limited to only pedicle screws, nor is the bone anchor head converter limited to engaging and / or cooperating only with pedicle screws. Such extenders may be configured to engage and / or work with both uniaxial and / or polyaxial types of bone anchors. As used herein, an "open style" bone anchor is one that has a "tulip head" in which a spinal fixation rod can be moved into, or secured within, the head, for example, via a receiving opening in the top of the tulip head. An example of an open-style bone anchor (or open-style pedicle screw) is a pedicle screw having a "tulip head" in which a spinal fixation rod can be moved into the channel 107, i.e., secured in the head, for example, through a receiving opening at the top of the tulip head, as described with respect to Figures 1-3 herein. As used herein, a "closed-style" bone anchor is a bone anchor screw having an opening through which a spinal fixation rod can be fed, for example, through a receiving opening on the side of the tulip head. An example of a "closed-style" bone anchor (or closed-style pedicle screw) is a pedicle screw having an opening through which a spinal fixation rod can be fed, for example, through a receiving opening on the side of the tulip head, as described with respect to Figure 4 herein.

[0027] Referring to FIG. 1, a representative open style pedicle screw 100 is shown. The open style pedicle screw 100 may be any of the known pedicle screws of a type often referred to as having a "tulip head." For purposes of this disclosure, the open style pedicle screw is described as including a screw shank 102, a neck 104, and a head 106, often referred to as a tulip head 106. The tulip head 106 may include first and second tulip arms 112 opposed to one another. The first and second tulip arms 112 may form a channel 107. The first and second tulip arms 112 may extend from a curved lower surface (e.g., rod seat 108) that defines a substantially U-shaped internal channel 107. The channel 107 may be configured to receive a spinal fixation rod (e.g., 122) and may include a channel axis. The channel axis can correspond to and coincide with the longitudinal axis of the spinal fixation rod when the spinal fixation rod is secured within the channel 107. The rod 122 can be prepared within the channel 107 until it rests on a portion of the open channel surface, such as the rod seat 108. The shank can have an inner diameter and an outer diameter, each of which is determined by the size of the screw and the depth of the threads 110 on the shank 102. The thread depth, pitch, and other dimensional features can be predetermined based on the requirements of the pedicle screw, as known in the art. That is, the illustrated bone screw sizes are for illustration only, and variations in shank length, thread diameter, thread pitch, thread length, number of thread leads, induced compression of the shank, etc. can be changed without departing from the scope of this disclosure.

[0028] Other components and features of the open style pedicle screw may include those that aid in the insertion and use of the pedicle screw, including the fixation of a spinal fixation rod. For example, as illustrated in the partial cross-sectional view of the tulip head 106 in FIG. 2, the tulip head 106 may include features for compatible operation with a driving tool (not shown) and a rod fixation device (not shown). As a specific example, the use of a rod fixation device as known in the art may include engaging the tulip head 106 to drive or fix a spinal fixation rod into the channel 107 and toward the rod seat 108, manipulating one or more vertebrae, and / or inserting a set screw into the pedicle screw tulip head 106 for temporary or static fixation of a spinal rod. To this end, the tulip head 106 may have various features, such as a gripping tab 112 and / or a pocket 114 for connection and manipulation of a driving tool and / or a rod fixation tool, as well as an internal thread 116 for receiving a set screw.

[0029] Referring now to FIG. 3, an open-style pedicle screw 100 is shown screwed into bone 118, the surface of which is representatively depicted by dashed line 120. The bone 118 can be a pedicle, and the pedicle screw 100 can be driven into the pedicle until the neck 104 is adjacent to the bone 118. In one embodiment, the pedicle can be undertapped for the appropriate screw size. After undertapping the pedicle, a flexible feeler probe can be used to confirm the presence of a screw in the tapped hole. To measure the hole length, the feeler probe is advanced to the bottom of the hole and a hemostat is clamped to the feeler probe just as it exits the pedicle. The appropriate screw diameter and length can then be selected based on preoperative measurements and intraoperative observations. The same procedure can be repeated for the remaining pedicles that need to be instrumented.

[0030] A rod fixation tool can be applied over the tulip head 106 of the screw. In one embodiment, the fingers of the rod fixation device can engage the pocket 114 of the tulip head 106 of the pedicle screw. The rod 122 can then be secured by the rod fixation device and set into the rod seat 108. A set screw driver can then be used to introduce a set screw 124. The set screw can be threaded through the rod fixation device and rotated until it bottoms out, securing the rod 122 to the tulip head 106.

[0031] As shown in FIG. 3, once the rod 122 is secured to the tulip head 106 and the set screw 124 is set, the distance D1 from the bone surface 120 and the axis 126 of the rod 122 are immovably fixed. However, due to spinal curvature or other forces imposed on the spinal fixation rod 122, the spinal fixation rod 122 may exert a force on it (upward as illustrated in FIG. 3). If too much force is exerted on the set screw 124, the set screw may break, thereby causing the spinal fixation rod 122 to become dislodged from its intended position. Another failure mode is splaying of the tulip head, which again results in loss of the threaded connection of the set screw 124 and loss of alignment of the spinal fixation rod 122.

[0032] Referring to FIG. 4, a representative embodiment of a closed style pedicle screw 200 is shown. For purposes of this disclosure, a closed style pedicle screw is described as including a screw shank 202, a neck 204, and a head 206. The head 206 is not an open tulip style head, but a closed head with a through hole opening 208 disposed therein. The through hole opening 208 allows a spinal fixation rod to be fed, passed through, and ultimately secured into the pedicle screw 200. As discussed above, for a closed style pedicle screw, the shank can have an inner diameter and an outer diameter, each of which is determined by the size of the screw and the depth of the threads 210 on the shank 202. The thread depth, pitch, and other dimensional features can be predetermined based on the requirements of the pedicle screw, as known in the art. That is, the bone screw sizes depicted are for illustrative purposes only, and variations in shank length, thread diameter, thread pitch, thread length, number of thread leads, induced compression of the shank, etc., may be altered without departing from the scope of this disclosure. As can be appreciated, although more difficult to accomplish, a closed style pedicle screw head can completely encircle the spinal fixation rod 124, thereby mitigating one or more of the set screw failure problems discussed above with respect to the open style pedicle screw heads.

[0033] With reference to FIG. 5, an exemplary embodiment of an open-style pedicle tulip head 106 is shown illustrating representative features that may be used for connectivity and manipulation and may be intended for such a screw to facilitate the use of driving tools and / or rod fixation tools. For the present disclosure, such features, and any other features of the kind, may be utilized to facilitate conversion from an open-style pedicle screw to a closed-style pedicle screw. As shown in FIG. 5, for example, the open-style pedicle tulip head 106 may have internal threads 116 and recessed portions, referred to herein as pockets 114, on various lateral surfaces 130 of the open-style pedicle tulip head 106. As will be more fully understood in light of the following description, the pockets 114 may be utilized for a secondary purpose, i.e., to facilitate conversion of the open-style pedicle screw to a pedicle screw having a closed head. Other types of open-style bone anchors, e.g., open-style bone hooks, may include one or more similar and / or same features as described above with reference to the pedicle screw 100.

[0034] In an illustrated embodiment of the present disclosure, a converter member is disclosed that can be coupled to an open style tulip head of a bone anchor. The term "coupled" or its derivatives means to operatively fit in a connected manner such that the open style tulip head is converted to operate as a closed style pedicle screw head. The coupling can be by adhesive, press fit, snap fit, threaded screw fit, and the like. In one embodiment, the converter member can be snap-fit ​​by having an extension (not shown) that snaps into a pocket to securely hold the converter member to the open style tulip head. In one embodiment, the converter member has dimensions designed for a particular open style tulip head such that a portion can resiliently extend over the top of the tulip head and snap into one or more pockets when pressed down sufficiently.

[0035] In embodiments, the converter member may be a one-piece unit, except in those embodiments in which a second portion set screw is utilized as described below. That is, the converter member may be a single-piece unit that may be made, for example, of a molded polymer. In one embodiment, the converter member may be injection molded of a polymeric material suitable for use in the human body. In general, the converter member may have a smooth surface with smooth contours. In the illustrated embodiment, terms such as "vertical," "up," "down," "upward," and "downward" are used in reference to the converter member in the orientation shown in the figures, and correspond to orientations commonly experienced and understood in the use of pedicle screws and related instruments. Similarly, for purposes of explanation, various planes are referenced in describing the relative orientations of features and surfaces. However, the term "plane" is not intended to imply flatness, smoothness, or other planar characteristics of the features and surfaces so described.

[0036] 6, a converter member 10 is disclosed that can be coupled to an open-style tulip head 106 to convert a bone anchor (e.g., a pedicle screw) into a bone anchor with the advantages of a closed-style bone anchor. Once converted, the bone anchor can be considered a closed-style bone anchor (e.g., a closed-style pedicle screw). The converter member 10 can be coupled to the open-style tulip head 106 by inserting and tightening a set screw (not shown, e.g., a set screw described below) in the axis A1 direction that engages the internal threads 116, or can be snap-fit ​​to the tulip head 106 by having an extension (not shown) that snaps into a pocket 114 to securely hold the converter member 10 to the open-style tulip head 106. The axis A1 can correspond to the longitudinal axis of the tulip head pedicle screw, as can be understood from the description herein. Once converted, the open-style pedicle tulip head 106 can securely hold a spinal fixation rod 122 with the advantages of a closed-style pedicle screw. In some embodiments, the converter member 10 effectively surrounds and secures the tulip head portion of the open style tulip head 106 to prevent spreading under the force imparted by the spinal fixation rod 122. Spreading causes the set screw 124 to loosen or release, thereby allowing the spinal fixation rod 122 to move or spring free from the pedicle tulip head 106.

[0037] In one embodiment, the converter member 10 can be a one-piece member having two operable portions that can be distinguished by intersecting longitudinal axial openings. The first portion 12 can be defined as the portion of the converter member 10 that at least partially surrounds a first portion axis A1 that, in operation, is associated with a longitudinal axis of the internal threads 116 for the set screw 124 of the tulip head 106. The first portion axis A1 can be coaxial with the opening of the set screw 124 of the tulip head 106. The second portion 20 can extend from and be integral with the first portion 12 and can be defined as the portion of the converter member 10 that at least partially surrounds a second portion axis A2 that, in operation, is associated with a longitudinal axis of the spinal fixation rod 122. In use, the axis A2 can be coaxial with the axis of the spinal fixation rod 122. The first portion axis A1 can be perpendicular and coplanar with the second portion axis A2.

[0038] The first portion 12 may be a ring-like member having an inner surface 14 and an outer surface 16, the inner surface and the outer surface being separated by a first portion thickness having a variable but average dimension T1, as shown in FIG. 7. The inner surface 14 may define a closed perimeter with at least a portion of the inner surface having a dimension greater than the outer diameter dimension of the tulip head 106, and may fit securely into an upper portion of the tulip head 106. The first portion 12 may have an extension that snaps into a pocket 114 to couple the converter member 10 to the tulip head 106. The closed perimeter of the inner surface 14 defines an opening 18 that surrounds the first portion axis A1, which may be coaxial with the set screw axis of the tulip head 106 in use. That is, the first portion axis A1 may be considered to be generally vertically oriented. In one embodiment, a tulip head set screw 124 (not shown) can be secured to the tulip head internal threads 116 through the first portion 12 of the converter member 10 for securement or additional securement to couple the converter member 10 to the tulip head 106. The tulip head set screw 124 can effectively countersink the first portion 12 of the converter member 10 and provide a secure connection of the converter member 10 to the tulip head 106. The tulip head set screw 124 can further provide a locking force against the spinal fixation rod 124.

[0039] The second portion 20 can extend laterally from the first portion 12 and can include a shaped surface 22 for contacting and additionally securing to the spinal fixation rod 122. The shaped surface 22 can be a generally smooth, partially cylindrical surface that defines the second portion axis A2. The shaped surface 22 can have dimensions that allow for intimate contact with the spinal fixation rod 122 when coupled to the tulip head 106.

[0040] 7, in one embodiment, the shaped surface 22 can have a shaped extension 24 that encapsulates a sufficient distance to traverse an included angle ANG1 of at least 10 degrees to 90 degrees, measured from a plane P1 in which the second portion axis A2 lies and perpendicular to axis A1, to a distal end of the shaped extension 24. As can be understood from the description herein, the shaped extension can partially encapsulate the spinal fixation rod 122 when the converter member 10 is seated and joined to the tulip head 106.

[0041] 6 and 7, the second portion 20 can have a second portion threaded opening 32 into which the second portion set screw 28 can be threaded, i.e., into the second portion internal threads 30. The second portion threaded opening 32 can be positioned in the second portion 20 such that the portion of the opening that exits the underside of the second portion 20 is where the surface of the spinal fixation rod 122 will sit when the converter member 10 is set in operation. In this way, when the second portion set screw 28 is tightened, it can sit against the surface of the spinal fixation rod 122, providing a more secure connection to the spinal fixation rod 122.

[0042] As can be seen from the description of the embodiment in Figures 6 and 7, when the converter member 10 is utilized with an open style tulip head 106, the spinal fixation rod 122 may be completely surrounded by a portion of the tulip head 106, specifically the rod seat 108, a portion of the tulip arm 112, and / or the shaped surface 22 of the converter member 10. The shaped extension 24 may provide additional surrounded coverage of the converter member 10 for additional fixation of the spinal fixation rod 122. In this manner, the converter member 10 effectively converts the open style tulip head 106 pedicle screw into a pedicle screw having a closed head. As described, the converter member 10 may reduce or eliminate the possibility of the tulip head spreading or the set screw 124 loosening under the force exerted by the spinal fixation rod 122.

[0043] In the method of use of the embodiment of the converter member 10 shown in Figures 6 and 7, the spinal fixation rod 122 can be secured to the tulip head in any known manner. Once the spinal fixation rod 122 is secured or close to final fixation, the converter member 10 can be placed over the tulip head 106 and pressed, snapped, screwed, or otherwise engaged, seated, and / or connected. In an embodiment, the converter member 10 can be placed proximate to the tulip head 106 but not fully seated. In an embodiment, the form extension 24 can be forced around and / or partially under the spinal fixation rod 122 during placement of the converter member 10 on the tulip head 106. Once the converter member 10 is placed over the tulip head 106 and in position relative to the spinal fixation rod 122, one or both of the tulip head set screw 124 and the second portion set screw 28 can be tightened to effect final fixation and convert the open style tulip head pedicle screw to a pedicle screw having a closed head.

[0044] Referring now to FIG. 8, a converter member 10 is shown that is similar in most respects to the converter member 10 described above with reference to FIGS. 6 and 7. For the sake of brevity, the description of the common elements will not be repeated. As shown in FIG. 8, the first portion 12 can have an upper surface that defines an opening 18 that surrounds a first portion axis A1 that can be coaxial with the longitudinal axis of the internal threads 116 of the tulip head set screw 124 (not shown) of the tulip head 106 in use. In the embodiment shown in FIG. 8, the tulip head set screw 124 can be driven coaxially along the axis A1 through the opening 18 to connect and / or secure the converter member 10 to the tulip head 106. In an embodiment, the periphery of the opening 18 can also have internal threads that can cooperate with the internal threads 116 of the tulip head 106.

[0045] 9, in one embodiment, the converter member 10 may have a generally saddle-shaped full-lobed configuration. The saddle-shaped full-lobed converter member 10 may be a one-piece member having two operable portions that may be distinguished by intersecting axial openings. The first portion 12 may be defined as having a surface substantially parallel to the first portion plane P2, and is the portion of the saddle-shaped full-lobed converter member 10 that defines a first portion opening 18 that, in operation, is associated with the longitudinal axis of the tulip head set screw 124 (not shown) and at least partially surrounds a first portion axis A1 that is perpendicular to the first portion plane P2. The second portion 20 can include at least one and can have one or more lobes (e.g., a first lobe 20A and a second lobe 20B), each extending downwardly from the first portion 12 in a spaced-apart, substantially parallel relationship and having a surface substantially parallel to the second portion plane P3, each having a shaped surface 22. In one embodiment, the shaped surface 22 can have a closed perimeter defining an enclosed opening 32 through which the spinal fixation rod 122 can be inserted and secured. The second portion plane P3 can be perpendicular to the first portion plane P2 and the second portion axis A2.

[0046] In one embodiment, the tulip head set screw 124 can be secured to the tulip head internal threads 116 through the first portion opening 18 of the first portion 12 of the saddle-shaped full lobe converter member 10 for fixation or additional fixation to couple and / or secure the converter member 10 to the tulip head 106. The tulip head set screw 124 can effectively countersink the first portion 12 of the converter member 10 to provide a secure connection of the converter member 10 to the tulip head 106. The tulip head set screw 124 can further provide a fixation force against the spinal fixation rod 124. In one embodiment, the periphery of the opening 18 can also have internal threads that can cooperate with the tulip head internal threads 116.

[0047] In operation, the first portion 12 of the saddle-shaped full-lobed converter member 10 can cover and partially surround the top of the tulip head 106. When attached to the tulip head 106, as shown in FIG. 9, the first portion axis A1 can be coaxial with the tulip head set screw 124 (not shown). The second portion 20 can be defined as the portion of the saddle-shaped full-lobed converter member 10 that defines at least one, and may be two, lobe openings 34, each at least partially surrounding and defining a second portion axis A2, which in operation is associated with the longitudinal axis of the spinal fixation rod 122. In use, the second portion axis A2 can be coaxial with the longitudinal axis of the spinal fixation rod 122. The first portion axis A1 can be perpendicular and coplanar with the second portion axis A2.

[0048] The first portion 12 of the saddle-shaped full-lobed converter member 10 can sit on the tulip head 106 and have a portion that surrounds the tulip head 106 to prevent the tulip head 106 from spreading when the force from the spinal fixation rod 122 is upward. The second portion 20 of the saddle-shaped converter member 10 can include one or two downwardly facing partial or full lobes (shown as complete first and second lobes 20A and / or 20B) that can be substantially parallel to a plane that can be perpendicular to the axis A2.

[0049] In a method of securing a spinal fixation rod 122, the saddle-style full lobe converter member 10 can be engaged and / or secured to the spinal fixation rod 122 by inserting the spinal fixation rod 122 through the opening(s) 32 via the first lobe 20A and / or second lobe 20B. Once the spinal fixation rod 122 is inserted or threaded through the opening 32, the saddle-style converter member 10 can be positioned over the tulip head 106 with axis A1 aligned with the longitudinal axis of the tulip head set. Once the saddle-style converter member 10 is positioned over the tulip head 106, a tulip head set screw 124 (not shown) can be threaded and tightened into the internal threads 116 to provide final fixation and convert the open-style tulip head pedicle screw into a pedicle screw having a closed head.

[0050] Referring now to FIG. 10, there is shown a saddle-shaped partial-lobed converter member 10 which is similar in most respects to the saddle-shaped full-lobed converter member 10 described above with reference to FIG. 9. For the sake of brevity, the description of all common elements will not be repeated. As shown in FIG. 10, the first portion 12 may have an upper surface defining an opening 18 surrounding and perpendicular to a first portion axis A1 which may be coaxial with a longitudinal axis of a tulip head set screw 124 (not shown) of the tulip head 106 in use. In the embodiment shown in FIG. 10, the tulip head set screw 124 may be coaxially driven along the axis A1 through the opening 18 to secure the converter member 10 to the tulip head 106.

[0051] The saddle-shaped partial lobe converter member 10 may be a one-piece member having two operable portions that may be distinguished by intersecting axial openings or profile faces. The first portion 12 may be defined as the portion of the saddle-shaped partial lobe converter member 10 that at least partially surrounds the first portion axis A1 and is associated in operation with the longitudinal axis of a tulip head set screw 124 (not shown). In one embodiment, the tulip head set screw 124 may be secured to the internal threads 116 (not shown) of the tulip head 106 through the first portion 12 of the saddle-shaped partial lobe converter member 10 for fastening or additional fastening to couple the saddle-shaped partial lobe converter member 10 to the tulip head 106. The tulip head set screw 124 may effectively countersink the countersunk first portion 12 of the saddle-shaped partial lobe converter member 10 and provide a secure connection of the saddle-shaped partial lobe converter member 10 to the tulip head 106. The tulip head set screw 124 can further provide a fixation force against movement of the spinal fixation rod 124 .

[0052] The first portion 12 of the saddle-shaped partial lobe converter member 10 may seat on the tulip head 106 to engage and / or at least assist in securing the converter member 10 to the tulip head, and may have a portion surrounding the tulip head 106 to prevent the tulip head 106 from spreading when the force from the spinal fixation rod 122 is upward. The second portion 20 of the saddle-shaped partial lobe converter member 10 may include one or two downwardly facing lobes 20A and 20B, each lobe defining a shaped surface 22 that may contact the spinal fixation rod 122 in operation. The second portion 20 may include at least one lobe 20A, and may have two lobes 20A and 20B, each lobe having a surface substantially parallel to the second portion plane P3, each having a shaped surface 22, the shaped surfaces 22 defining a partial perimeter of an opening 32 in which the spinal fixation rod 122 may be secured. The second partial plane P3 may be perpendicular to the second partial plane P2 and parallel to the axis A1.

[0053] In a method of securing the spinal fixation rod 122, the saddle-shaped partial lobe converter member 10 can be placed over the tulip head 106 and over the spinal fixation rod 122 until one or more of the lobes 20A or 20B contacts the spinal fixation rod 122. Once the saddle-shaped partial lobe converter member 10 is placed over the tulip head 106, a tulip head head set screw 124 (not shown) can be threaded into the internal threads 116 and tightened for final fixation to convert the open-style tulip head pedicle screw into a pedicle screw having a closed head.

[0054] In operation, the first portion 12 of the saddle-shaped partial lobe converter member 10 covers and at least partially surrounds the top surface of the tulip head 106, as shown in FIG. 10, when attached to the tulip head 106, the first portion axis A1 can be coaxial with the tulip head set screw 124 (not shown). Additionally, when attached, the axis A2 can be coaxial with the longitudinal axis of the spinal fixation rod 122 (not shown). The first portion axis A1 can be perpendicular and coplanar with the second portion axis A2. As can be seen from the above description, when operatively installed, the saddle-shaped partial lobe converter member 10 converts an open-style tulip head pedicle screw into a pedicle screw having a closed head.

[0055] 11, there is shown one embodiment of a cap style converter member 10 that can be threaded onto the top of the tulip head 106. In a sense, the cap style converter member 10 can be thought of as a replacement for the tulip head set screw 124, but includes additional features that facilitate converting an open style tulip head pedicle screw into a pedicle screw having a closed head.

[0056] As shown in cross-section in Figures 11 and 12, the capped converter member 10 can have a first portion 12 that can cover and partially surround the tulip head 106. The second portion 20 can be a generally circular lip that can surround the tulip head 106 and prevent spreading forces SF that open the tulip head 106 during forces exerted by a spinal fixation rod 122. The capped converter member 10 can have external threads 36 that extend downwardly from the first portion 12 and inwardly to the lip of the second portion 20 and can be spaced inwardly a sufficient distance to allow a portion of the tulip head 106 to extend between the external threads 36 and an inner surface 38 of the circular lip. The outer threads 36 can be fitted and threaded into the tulip head inner threads 116 such that the capped converter member 10 can be threaded down onto, into and above the tulip head 106, thereby stably securing the spinal fixation rod 122 for final fixation of the open-style tulip head pedicle screw and conversion to a pedicle screw with a closed head.

[0057] In a method of fixing the spinal fixation rod 122, the cap style converter member 10 can be placed over the tulip head 106 and screwed into the tulip head 106 with the circular lip on the outside of the tulip head 106. Once the cap style converter member 10 is screwed into the tulip head 106, it can be tightened for final fixation, converting the open style tulip head pedicle screw into a closed head pedicle screw.

[0058] 13, there is shown an embodiment of a converter member that can be snapped into place on the tulip head 106 and / or screwed into place via a set screw 40, which in an embodiment can be a tulip head set screw 124. As with the embodiments described above, the converter member 10 illustrated in FIG. 13 can be a one-piece member having two operable portions that can be distinguished by intersecting axial openings. The first portion 12 can be defined as the portion of the converter member 10 that at least partially surrounds a first portion axis A1 that, in operation, is associated with the longitudinal axis of the tulip head internal threads 116 and / or set screw 124 of the tulip head 106. In operation, the first portion axis A1 can be coaxial with the opening of the set screw 124 of the tulip head 106. The second portion 20 can be defined as the portion of the converter member 10 that extends downwardly from the first portion 12 and at least partially surrounds and defines a second portion axis A2, which, in operation, is associated with the longitudinal axis of the spinal fixation rod 122. In use, the axis A2 may be coaxial with the longitudinal axis of the spinal fixation rod 122. The first portion axis A1 may be perpendicular to and coplanar with the second portion axis A2.

[0059] The first portion 12 may be a ring-like member having a top surface parallel to the first portion plane P2, an inner surface 14, and an outer surface 16, the inner surface and the outer surface being separated by a first portion thickness that may vary but has an average dimension T1 (similar to that shown in FIG. 7). The inner surface 14 may have a dimension greater than the outer diameter dimension of the tulip head 106 and may define a complete perimeter with at least a portion of the inner surface capable of fitting over an upper portion of the tulip head 106. The first portion 12 may have extensions or slots that snap into pockets 114 or over protrusions, respectively, of the tulip head 106 to couple and / or connect the converter member 10 to the tulip head 106. The inner surface 14 defines an opening 18 that surrounds and defines a first portion axis A1, which may be coaxial with the axis of the set screw 124 of the tulip head 106 in use. That is, the first portion axis A1 may be considered to be generally oriented vertically. In one embodiment, a first portion set screw 40 (not shown) can be secured through the first portion 12 of the converter member 10 to the internal threads 116 of the tulip head for securement or additional securement for coupling the converter member 10 to the tulip head 106. The first portion set screw 40 can effectively countersink the first portion 12 of the converter member 10 and provide a secure connection of the converter member 10 to the tulip head 106. The first portion set screw 40 can also provide a locking force against the spinal fixation rod 124.

[0060] The second portion 20 can extend downwardly from the first portion 12 and can include a shaped surface 22 for contacting and / or securing to a spinal fixation rod 122. The shaped surface 22 can be a generally smooth partial cylindrical shaped surface that defines a central axis A2. The shaped surface 22 can have dimensions that allow for intimate contact with the spinal fixation rod 122 when coupled to the tulip head 106.

[0061] 7, in an embodiment, the shape surface 22 can have a shape extension 24 that wraps a sufficient distance to traverse an included angle ANG1 (ANGLE 1) of at least 10 degrees to 100 degrees, measured from a plane P1 in which the second portion axis A2 lies and perpendicular to the axis A1. As can be understood from the description herein, the shape extension can partially wrap around the spinal fixation rod 122 when the converter member 10 is seated and engaged and / or coupled to the tulip head 106. A positive snap of the tulip head 106 into a pocket or protrusion and / or a positive tightening of the first portion set screw 40 secures the converter member to the tulip head 106, converting the open style tulip head pedicle screw into a pedicle screw having a closed head.

[0062] An open-style tulip head pedicle screw may be converted to a closed-style pedicle screw prior to insertion of a spinal fixation rod. Generally, the conversion may be accomplished by a method for converting an open-style tulip head pedicle screw to a closed-style pedicle screw as disclosed herein and illustrated in process 140 described with reference to FIG. 14. In step 142, an open-style tulip head of a pedicle screw may be provided having internal threads defining a set screw axis. The open-style tulip head may have an upper surface and a channel-like opening extending from the opening to a rod seat surface, the channel-like opening including internal threads for receiving a tulip head set screw along the tulip head set screw axis. In step 144, a converter member may be provided as disclosed herein. The converter member may include a first portion coupled to a second portion, the first portion having a surface parallel to a first portion plane and an opening defining a first portion axis. The converter may include a first portion having a first portion axis and a second portion extending from the first portion, the second portion having a second portion axis perpendicular and coplanar to the first portion axis. The second portion may extend from the first portion and have a surface parallel to a second portion plane. The second portion plane may be perpendicular to the first portion plane, and the second portion has a curved surface defining a second portion axis, the second portion axis perpendicular and coplanar to the first axis. In step 146, the converter member may be mated to the open style tulip head by translating the converter member onto the open style tulip head such that the first portion axis is aligned with a set screw axis of the tulip head. Optionally, in step 148, a set screw may be provided and used to thread into the internal threads of the open style tulip head to secure the converter member to the open style tulip head.

[0063] The foregoing description of the embodiments and examples has been presented for purposes of illustration and description. It is not intended to be exhaustive or limiting to the forms described. Numerous modifications are possible in light of the above teachings. Some of these modifications have been discussed, and others will be appreciated by those skilled in the art. The embodiments were selected and described in order to best explain the principles of the various embodiments as suited to the particular applications contemplated. Of course, the scope is not limited to the examples described herein, and may be adopted by those skilled in the art in any number of applications and equivalent arrangements. Rather, it is intended herein that the scope of the invention be defined by the appended claims.

Claims

1. A one-piece, saddle-shaped partial lobe pedicle screw tulip head converter, comprising: a first portion and a second portion extending from the first portion; Equipped with the first portion has a surface parallel to a first portion plane and a first portion opening defining a first portion axis perpendicular to the first portion plane; the second portion includes a first lobe extending downwardly from the first portion and a second lobe extending downwardly from the first portion in spaced parallel relationship with the first lobe; each of the first and second lobes has a surface parallel to a second partial plane, the second partial plane being perpendicular to the first partial plane; each of the first and second lobes having a contoured surface defining a second portion axis, the contoured surface configured to engage a spinal fixation rod, the second portion axis being perpendicular to and coplanar with the first portion axis; the contoured surface of each of the first and second lobes only partially circumscribes the second portion axis; A pedicle screw tulip head converter configured to at least partially surround an upper portion of the tulip head.

2. The pedicle screw tulip head converter of claim 1 , wherein the first portion opening includes a countersink configured to receive a tulip head set screw.

3. The pedicle screw to tulip head converter of claim 1 , wherein the first and second lobes are configured to receive the tulip head therebetween.

4. The pedicle screw tulip head converter of claim 3, wherein when the pedicle screw tulip head converter is placed on the tulip head, a tulip head set screw is threaded into the internal threads and tightened for final fixation, thereby converting the open style tulip head pedicle screw into a pedicle screw having a closed head.

5. A cap-type converter, a first portion configured to cover and partially surround the tulip head; a second portion having a circular lip, the lip configured to surround the tulip head, the lip having an inner surface; and external threads extending downwardly from said first portion and inwardly of said second portion, said external threads spaced inwardly a sufficient distance so that a portion of said tulip head extends between said external threads and said inner surface of said lip; Equipped with A capped converter, wherein the external threads are configured to engage with the internal threads of the tulip head.

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