Patent Description:
In general, a pedicle screw can have a head with a receiving opening into which a spinal rod can be secured. The open head of a pedicle screw of this type is often referred to as a "tulip head. " An open style tulip-head pedicle screw permits a spinal fixation rod to be translated, i.e., "reduced" into the tulip head via the receiving opening after the pedicle screw has been screwed into the pedicle bone. Once reduced, a set screw can be screwed into threads internally disposed in the receiving opening, effectively closing the opening and fixing the spinal fixation rod into the pedicle screw.

Pedicle screws can also be of the "closed head" style, in which the head is not open to receive a rod translated, or reduced, therein. Rather, the screw head has an opening, i.e., a through hole, through which a spinal fixation rod can be fed, and thereby fixed to the pedicle screw. It is believed that closed head style pedicle screws can withstand greater forces exerted by the spinal fixation rod on the pedicle screw. For example, it is believed that closed head style ORT <NUM> <CIT> OP06K02 <CIT> pedicle screws can withstand greater forces exerted by the spinal fixation rod, forces which could cause open tulip style heads to splay, thereby permitting the spinal fixation rod to move out of its fixed position.

At times, a surgeon may wish to utilize a closed style pedicle screw where an open style tulip head has previously been set, i.e., screwed into a portion of the pedicle bone. It can be the case that during the process of spinal fixation it is discovered that an existing open style tulip head is not desirable, but removing it and replacing it with a closed style head can both add additional surgery time and cause additional trauma to the bone during the screw replacement process.

<CIT> is directed to a device for securing a spinal rod to a fixation device such as a pedicle screw or a lamina hook. The device disclosed herein includes a head portion configured to receive a spinal rod, a locking cap configured to engage the head portion and the spinal rod upon rotation of the locking cap relative to the head portion to secure the position of the head portion and the locking cap relative to the spinal rod, and a fastener portion extending from the head portion and configured to engage the spine. The fastener portion of the device can be in the form of a screw, hook or clamp, or any other configuration known in the art.

Accordingly, there remains an unmet need for an apparatus, system, and method to provide for improved bone anchors.

The present invention relates to a unitary saddle-shaped pedicle screw tulip head converter, the converter comprising: a first portion and a second portion extending from the first portion, the first portion having a surface parallel to a first portion plane, and a first portion opening defining a first portion axis perpendicular to the first portion plane, wherein the first portion opening is, in operation, associated with the longitudinal axis of a tulip head set screw, the second portion comprising at least one lobe extending downwardly from the first portion, the at least one lobe having a surface parallel to a second portion plane, the second portion plane being perpendicular to the first portion plane, the at least one lobe having a shaped surface for contacting and additional securement of a spinal fixation rod which is reducible into the pedicle screw tulip head, the spinal fixation rod defining a second portion axis, the second portion axis being perpendicular to and coplanar with the first portion axis, wherein the shaped surface of the at least one lobe comprises a closed perimeter defining an enclosed opening through which the spinal fixation rod can be inserted and secured.

The present disclosure will be more readily understood from a detailed description of some example embodiments taken in conjunction with the following figures:.

Various non-limiting embodiments of the present disclosure will now be described to provide an overall understanding of the principles of the structure, function, and use of the apparatuses, systems, methods (these methods not being claimed), and processes disclosed herein. One or more examples of these non-limiting embodiments are illustrated in the accompanying drawings. Those of ordinary skill in the art will understand that systems and methods specifically described herein and illustrated in.

The examples discussed herein are examples only and are provided to assist in the explanation of the apparatuses, devices, systems and methods described herein. None of the features or components shown in the drawings or discussed below should be taken as mandatory for any specific implementation of any of these the apparatuses, devices, systems or methods unless specifically designated as mandatory. For ease of reading and clarity, certain components, modules, or methods may be described solely in connection with a specific figure. Any failure to specifically describe a combination or sub-combination of components should not be understood as an indication that any combination or sub-combination is not possible. Also, for any methods described, regardless of whether the method is described in conjunction with a flow diagram, it should be understood that unless otherwise specified or required by context, any explicit or implicit ordering of steps performed in the execution of a method does not imply that those steps must be performed in the order presented but instead may be performed in a different order or in parallel.

Described herein are example embodiments of bone anchors (e.g., anchors, screws, etc.) useful for orthopedic procedures such as, for example, spinal fixation. In the illustrated embodiments a pedicle screw is disclosed to teach the features and benefits of a bone screw, but the disclosure is not to be limited only to pedicle screws, nor are the bone anchor head converters limited to engaging and/or working with only pedicle screws. Such extenders may configured to engage and/or work with any type of bone anchor, both mono-axial and/or polyaxial. As used herein, an "open style" bone anchor is a bone anchor having a "tulip head" in which a spinal fixation rod can be translated into, i.e., reduced into the head through a receiving opening at, for example, the top of the tulip head. One 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 translated into, i.e., reduced into the head through a receiving opening at, for example, the top of the tulip head and into channel <NUM>, as described with respect to <FIG> 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 through a receiving opening at, for example, a side of the tulip head. One 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 through a receiving opening at, for example, a side of the tulip head, as described with respect to <FIG> herein.

Referring to <FIG>, a representative open style pedicle screw <NUM> is shown. Open style pedicle screw <NUM> can be any of known pedicle screws of the type often referred to as having "tulip heads. " For the purposes of the present disclosure, the open style pedicle screw is described as including a screw shank <NUM>, a neck <NUM>, a head <NUM>, which is often referred to as a tulip head <NUM>. The tulip head <NUM> can include first and second tulip arms <NUM> opposed from each other. First and second tulip arms can form a channel <NUM>. First and second tulip arms <NUM> can extend from a curved lower surface (e.g., rod seat <NUM>) defining the substantially U-shaped interior channel <NUM>. The channel <NUM> can be constructed to receive a spinal fixation rod (e.g., <NUM>) and can include a channel axis. The channel axis can correspond to, and be coincident with, a longitudinal axis of a spinal fixation rod when it is reduced into the channel <NUM>. The rod <NUM> can be reduced into the channel <NUM> until it rests on a portion of the open channel surface, e.g., the rod seat <NUM>. The shank can have an inner diameter and an outer diameter, the inner diameter and outer diameter each being determined by the size of the screw and the depth of threads <NUM> on shank <NUM>. The thread depth, pitch, and other dimensional features can be predetermined based on the requirements of the pedicle screw, as is known in the art. That is, the proportions of the bone screw depicted are for illustrative purposes only and variations in the length of the shank, diameter of the screw, thread pitch, thread length, number of thread leads, shank induced compression and the like may be varied.

Other components and features of an open style pedicle screw can be included that aid in insertion and use of the pedicle screw, including spinal fixation rod reduction. For example, as depicted in the partial cross-sectional view of tulip head <NUM> in <FIG>, tulip head <NUM> can include features for compatible operation with driving tool (not shown) and a rod reduction device (not shown). As a specific example, a rod reduction device, as is known in the art, may be used to engage with tulip head <NUM> to urge, or reduce, a spinal fixation rod into the channel <NUM> and toward the rod seat <NUM>, manipulate one or more vertebrae, and/or insert a set screw for temporary or stationary fixation of the spinal rod into the pedicle screw tulip head <NUM>. For this reason, tulip head <NUM> can have various features, such as grasping tabs <NUM> and/or pockets <NUM>, for connectivity and operation of the driving tool and/or rod reducing tool, and internal threads <NUM> for receiving a set screw.

Referring now to <FIG>, there is shown an open style pedicle screw <NUM> screwed into a bone <NUM>, the surface of which is representatively depicted by the dashed line <NUM>. Bone <NUM> can be a pedicle, and pedicle screw <NUM> can be driven into the pedicle until the neck <NUM> is adjacent the bone <NUM>. In an embodiment, the pedicle can be undertapped for the appropriate screw size. After the pedicle is undertapped a flexible feeler probe may be used to verify presence of threads in the tapped hole. To measure the length of the hole, a feeler probe is advanced to the floor of the hole and a hemostat is clamped to the feeler probe at the point where it exits the pedicle. The appropriate screw diameter and length may subsequently be selected based on both preoperative measurement and intraoperative observation. The same technique can be repeated for any remaining pedicles that need to be instrumented.

A rod reduction tool can be applied over the tulip head <NUM> of the screw. In an embodiment, fingers of the rod reduction device can engage the pockets <NUM> of the pedicle screw tulip head <NUM>. The rod <NUM> can then be reduced by the rod reduction device to set in rod seat <NUM>. A set screw driver can then be used to introduce a set screw <NUM>. The set screw can be passed through the rod reduction device and rotated until it bottoms out, securing rod <NUM> into the tulip head <NUM>.

As depicted in <FIG>, once rod <NUM> is reduced into tulip head <NUM> and set screw <NUM> is set, the distance D1 from bone surface <NUM> and the axial center <NUM> of rod <NUM> is immovably fixed. However, due to spinal curvature or other forces imposed on the spinal fixation rod <NUM>, the spinal fixation rod <NUM> can have exerted thereon forces against the set screw <NUM> (upwardly as depicted in <FIG>). If the forces exerted against set screw <NUM> become too great the set screw can fail, thereby allowing the spinal fixation rod <NUM> to move out of place. Another mode of failure can be splaying of the tulip head, which also results in loss threaded connection of the set screw <NUM>, and loss of placement of the spinal fixation rod <NUM>.

Referring to <FIG> there is shown a representative embodiment of a closed style pedicle screw <NUM>. For the purposes of the present disclosure, the closed style pedicle screw is described as including a screw shank <NUM>, a neck <NUM>, and a head <NUM>. The head <NUM>, rather than being an open tulip style head, is a closed head that includes a through hole opening <NUM> disposed therethrough. This through hole opening <NUM> can allow a spinal fixation rod to be fed into, fed through, and ultimately, secured to the pedicle screw <NUM>. As discussed above, for closed style pedicle screws, the shank can have an inner diameter and an outer diameter, the inner diameter and outer diameter each being determined by the size of the screw and the depth of threads <NUM> on shank <NUM>. The thread depth, pitch, and other dimensional features can be predetermined based on the requirements of the pedicle screw, as is known in the art. That is, the proportions of the bone screw depicted are for illustrative purposes only and variations in the length of the shank, diameter of the screw, thread pitch, thread length, number of thread leads, shank induced compression and the like may be varied without departing from the scope of the disclosure. As can be understood, although more difficult to work with, the closed style pedicle screw head can completely surround the spinal fixation rod <NUM>, thereby alleviating one or more of the problems of set screw failure discussed above with respect to open style pedicle screw heads.

Referring to <FIG>, there is shown an example embodiment of an open style pedicle tulip head <NUM> showing representative features that can be used for connectivity and operation, and can be intended on such a screw to facilitate the driving tool and/or rod reducing tool. For the present disclosure such features, and any other features of their kind, can be utilized to facilitate conversion of an open style pedicle screw to a closed style pedicle screw. As shown in <FIG>, for example, an open style pedicle tulip head <NUM> can have internal threads <NUM> and indented portions, referred to herein as pockets <NUM> on various lateral surfaces <NUM> of the open style pedicle tulip head <NUM>. As will be more fully understood in light of the description below, pockets <NUM> can be utilized for secondary purposes, i.e., to facilitate the conversion of an open style pedicle screw into 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 the same features as described above with reference to the pedicle screw <NUM>.

In illustrated embodiments of the present disclosure a converter member is disclosed that can be joined to an open style tulip head of a bone anchor. The term "joined" or its derivatives means operatively mated in a connecting manner such that an open style tulip head is converted to operate as a closed style pedicle screw head. Joining can be by adhesive, press fit, snap fit, threaded screw fit, and the like. In an embodiment, converter member can be snap fit by having extensions (not shown) that snap into pockets to securely hold converter member to open style tulip head. In an embodiment, converter member has dimensions designed for a particular open style tulip head such that portions can elastically extend over the top of the tulip head and, when pushed sufficiently down, snap into one or more pockets.

In an embodiment, a converter member can be an integral unit, except for embodiments in which a second portion set screw is utilized, as described below. That is, converter member can be a single piece unit that can be, for example, made of molded polymer. In an embodiment converter member can be injection molded of a polymer material suitable for use in a human body. In general, the converter member can be smooth sided, having smooth contours. In the illustrated embodiments, terms such as "vertical," "upper," "lower" "upwardly," and "downwardly" are used in relation to the converter member in the orientation shown in the FIGS, and corresponding to the orientation generally experienced and understood in the use of pedicle screws and related instrumentation. Likewise, for descriptive purposes various planes are referred in describing relative orientations of features and surfaces. However, the term "plane" is not intended to imply any flatness, smoothness, or other planar characteristics to the features and surfaces so described.

Referring now to <FIG>, in an embodiment converter member <NUM> can have a generally saddle-shaped, full-lobed configuration. Saddle-shaped, full-lobed converter member <NUM> can be a unitary member having two operative portions that can be distinguished by intersecting axially oriented openings. A first portion <NUM> can be defined as having a surface substantially parallel to a first portion plane P2, and which is the part of saddle-shaped, full-lobed converter member <NUM> that defines a first portion opening <NUM> that at least partially surrounds a first portion axis A1, which in operation is associated with a longitudinal axis of tulip head set screw <NUM> (not shown) and is perpendicular to first portion plane P2. A second portion <NUM> can include at least one, and can have one or more lobes (e.g., a first lobe 20A and a second lobe 20B), with each lobe extending downwardly in a spaced, substantially parallel relationship, from first portion <NUM> and having a surface substantially parallel to a second portion plane P3, and each having a shaped surface <NUM>. In an embodiment, the shaped surface <NUM> can have a closed perimeter defining an enclosed opening <NUM> through which spinal fixation rod <NUM> can be inserted and secured. Second portion plane P3 can be perpendicular to first portion plane P2 and second portion axis A2.

In an embodiment, tulip head set screw <NUM> can be secured through first portion opening <NUM> of first portion <NUM> of saddle-shaped, full-lobed converter member <NUM> to internal threads <NUM> of tulip head for securement, or additional securement, to join and/or secure the converter member <NUM> to tulip head <NUM>. The tulip head set screw <NUM> can be effectively counter-sunk into the first portion <NUM> of converter member <NUM> and provide for secure joining of the converter member <NUM> to the tulip head <NUM>. Tulip head set screw <NUM> can additionally supply securement forces against spinal fixation rod <NUM>. In an embodiment, the perimeter of opening <NUM> can also have internal threads that can work in conjunction with the internal threads <NUM> of tulip head <NUM>.

In operation, first portion <NUM> of saddle-shaped, full-lobed converter member <NUM> can cover and partially surround the top of tulip head <NUM>. When installed on a tulip head <NUM>, as shown in <FIG>, first portion axis A1 can be coaxial with the tulip head set screw <NUM> (not shown). Second portion <NUM> can be defined as the part of saddle shaped, full-lobed converter member <NUM> that defines at least one, and can be two, lobe openings <NUM>, each lobe opening at least partially surrounding and defining a second portion axis A2, which in operation is associated with the longitudinal axis of spinal fixation rod <NUM>. When in use, second portion axis A2 can be coaxial with the longitudinal axis of spinal fixation rod <NUM>. First portion axis A1 can be perpendicular and co-planar with second portion axis A2.

First portion <NUM> of saddle-shaped, full-lobed converter member <NUM> can seat on top of tulip head <NUM>, having a portion that surrounds tulip head <NUM> to prevent splaying of tulip head <NUM> when forces from spinal fixation rod <NUM> are upward. Second portion <NUM> of saddle-shaped converter member <NUM> can include one or two downward-oriented partial or full lobes (shown as full first and second lobes 20A and/or 20B) that can be substantially parallel to a plane that can be perpendicular to axis A2.

Claim 1:
A unitary saddle-shaped pedicle screw tulip head converter (<NUM>), the converter (<NUM>) comprising:
a first portion (<NUM>) and a second portion (<NUM>) extending from the first portion (<NUM>),
the first portion (<NUM>) having a surface parallel to a first portion plane (P2), and a first portion opening (<NUM>) defining a first portion axis (A1) perpendicular to the first portion plane (P2),
wherein the first portion opening (<NUM>) is, in operation, associated with the longitudinal axis of a tulip head set screw (<NUM>),
the second portion (<NUM>) comprising at least one lobe (20A) extending downwardly from the first portion (<NUM>), the at least one lobe (20A) having a surface parallel to a second portion plane (P3), the second portion plane (P3) being perpendicular to the first portion plane (P2), the at least one lobe (20A) having a shaped surface (<NUM>) for contacting and additional securement of a spinal fixation rod (<NUM>) which is reducible into the pedicle screw tulip head (<NUM>), the spinal fixation rod (<NUM>) defining a second portion axis (A2), the second portion axis (A2) being perpendicular to and coplanar with the first portion axis (A1), characterized in that the shaped surface (<NUM>) of the at least one lobe (20A) comprises a closed perimeter defining an enclosed opening (<NUM>) through which the spinal fixation rod (<NUM>) can be inserted and secured.