Patent Description:
Spinal fixation systems may be used to surgically fix, adjust, and/or align the spinal column. One type of spinal fixation system employs a spinal rod for supporting the spine and fixing, adjusting, and/or aligning all or portions of the spinal column into a desired orientation. Attachment of the spinal rod to the spinal column has been achieved using a variety of vertebral anchors. Pedicle screws have been used successfully as vertebral anchors. Pedicle screws and connectors in combination with spinal rods can align and correct deformities in the natural spinal alignment as well as repair traumatic injury. In general, a pedicle screw has a head with a receiving opening into which a spinal rod can be secured. From <CIT>, a head extender for use with a pedicle screw to ease connection to a spinal rod is known. The pedicle screw head extenders provided in <CIT> can be used with either fixed head pedicle screws or multi-axial head pedicle screws. The pedicle screw head extenders can either be threaded to or snapped into place within the various pedicle screws. It may also be possible to use the present invention with other types of spinal screws that may be connected to spinal rods without the screw actually being implanted through the pedicle of the spine. Further examples of head extenders for use with pedicle screws are disclosed by <CIT>, <CIT> and <CIT>.

However, once a pedicle screw is set, i.e., screwed into a portion of the pedicle bone, the location of a spinal rod to be set into it is also set due to the fixed position of the head of the pedicle screw. It can be the case that during the process of spinal fixation it is discovered that the fixed location of the head of the pedicle screw, and, therefore, the fixed location of the reduced spinal rod, is not ideal.

Accordingly, there remains an unmet need for an apparatus, system, and method to provide for variable positioning of a spinal rod in a fixed pedicle screw.

Further, there remains an unmet need for spinal fixation apparatus that permits greater flexibility for neuromuscular and revision cases by providing for a greater variety of instrumentation.

The present invention provides a pedicle screw tulip head extender according to claim <NUM>.

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

The embodiments which form part of the invention are illustrated in the <FIG>.

The examples shown in the other figures do not form part of the invention but represent background art that is useful for understanding the invention.

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, and processes disclosed herein. One or more examples of these non-limiting embodiments are illustrated in the accompanying drawings.

Described herein are embodiments of bone anchors (e.g., hooks, 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 of a bone anchor and how the one or more embodiments of tulip head extenders engage and/or work with such illustrative pedicle screws. , but the disclosure is not to be limited only to pedicle screws, nor are the tulip head extenders limited to engaging and/or working with only pedicle screws.

Referring to <FIG>, a representative pedicle screw <NUM> is shown. Pedicle screw <NUM> can be any of known pedicle screws with any of known beneficial features for installation and use in processes and systems such as, for example, of spinal fixation. For the purposes of the present disclosure, the 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 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 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 pedicle screw depicted are for illustrative purposes only and variations in the length, shape, and/or configuration of such pedicle screw may vary such as, for example, the shape and size of the head, 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.

Other components and features of a pedicle screw may be included that aid in its insertion into a bone and its use. For example, as depicted in the partial cross-sectional view of tulip head <NUM> in <FIG>, tulip head <NUM> may 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 and/or pockets <NUM>, for connectivity and operation of the driving tool, rod reducing tool, and/or other instruments, and internal threads <NUM> for receiving a set screw or other implants and/or instruments.

Referring now to <FIG>, there is shown a 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 inserted and/or 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. As illustrated, the distance D1 is shown as extending to the axial center of the rod <NUM>, but for description purposes the dimensions D1, as well as D2 and D3 described below, can be measured to the top or bottom of the rod without departing from the scope of the disclosure.

Referring to <FIG> there is shown an embodiment of a pedicle screw tulip head extender <NUM> that, when engaged to and/or installed into tulip head <NUM>, can facilitate the repositioning of rod <NUM> with respect to bone surface <NUM> from a distance D1 an additional distance D2, for a total distance D3. As can be understood, extender <NUM> permits the vertical repositioning of rod <NUM> from an original position shown as <NUM>' without disturbing pedicle screw <NUM>. The distance D2 can be predetermined by varying the geometry of extender <NUM>, as will be more fully understood in light of the description below.

An embodiment of pedicle screw tulip head extender <NUM> as shown in <FIG> is depicted in more detail in <FIG>. In the illustrated embodiments, terms such as "vertical," "upper," "lower" "upwardly," and "downwardly" are used in relation to the extender <NUM> in the orientation shown in the FIGS, and corresponding to the orientation generally experienced in use of pedicle screws and related instrumentation. Extender <NUM> has an upper body portion <NUM> joined to a lower body portion <NUM>. The upper body portion <NUM> can be integrally formed with lower body portion <NUM>, such as by machining from a blank, injection molding, etc., or the two parts can be manufactured separately and joined by adhesive, welding, press fit, or the like. Upper body portion <NUM> has a first extender arm <NUM> and a second extender arm <NUM> opposed to the first extender arm. First extender arm <NUM> and second extender arm <NUM> extend from a curved lower surface defining a substantially U-shaped interior channel <NUM> that has a first channel axis <NUM>. The first channel axis <NUM> can correspond to, and be coincident with, a longitudinal axis of a rod <NUM> when reduced into extender <NUM>. The first interior threads <NUM> of first and second extender arms can be complementary to receive an appropriately sized set screw (not shown). As can be understood from the description above, first and second extender arms <NUM> and <NUM>, first interior threads <NUM>, and interior channel <NUM> correspond to the same or similar functional features of a tulip head, such as tulip head <NUM> of pedicle screw <NUM>. As can be further understood, the features of the upper portion <NUM> of extender <NUM> can include any features <NUM> desired or required on illustrative bone anchors such as, for example, pockets, tabs, indentations, and openings, to engage with a variety of instruments such as, for example, a particular rod reducing tool, and, as such, facilitate rod reduction by known techniques, albeit reducing the rod a shorter distance than what would have been required to reduce it to the original rod seat <NUM> (e.g., <FIG> and <FIG>).

Lower portion <NUM> extends downwardly from the upper portion <NUM>, and has a portion sized to fit into the channel <NUM> and seat on the rod surface <NUM> of tulip head <NUM> of pedicle screw <NUM>. That is, lower portion <NUM> can be a substantially U-shaped protrusion, joined to upper portion <NUM> by generally parallel spaced apart first and second U-shaped sides, <NUM> and <NUM> (side <NUM> on the side not seen in <FIG>). First and second U-shaped sides can be substantially identical in size and shape and have a protrusion width PW having a dimension sized according to the channel width of the tulip head <NUM> of the pedicle screw <NUM>. First and second U-shaped sides can be spaced apart a distance defining a protrusion depth PD, the protrusion depth PD being a dimension suitable for stable securement to the tulip head <NUM> of pedicle screw <NUM>, and can be predetermined based on the sizing and requirements of related instrumentation. First and second sides <NUM> and <NUM> need not be U-shaped, but can have any shape constrained only in that the lower portion <NUM> be able to be insertable into and seat with the tulip head <NUM> of a pedicle screw <NUM> (e.g., channel <NUM> and seat <NUM>). Thus, first and second sides <NUM> and <NUM> can have rectangular shape, for example, and remain functionally capable of being seated into the tulip head <NUM> of pedicle screw <NUM>.

The extender <NUM> can have first and second surfaces <NUM> and <NUM>, which can be generally horizontally oriented portions of the lower surface of upper portion <NUM>, and which can abut the top surface of tulip head <NUM> of pedicle screw <NUM> when the extender <NUM> is set into place. Although in some embodiments, the extender <NUM> may not have first and second surfaces <NUM> and <NUM> or such surface may not be generally horizontally oriented. In some embodiments, first and second sides <NUM> and <NUM> can extend a distance Ll below and generally perpendicular to first and second surfaces <NUM> and <NUM> to the bottom of the U-shaped sides. Distance Ll can be substantially equal to the depth of the channel having the rod seat <NUM> of tulip head <NUM>. Curved lower surface <NUM> of upper portion <NUM> of extender <NUM> can be a distance L2 measured from the bottom of the U-shaped first and second sides <NUM> and <NUM>. Distance L2 can be greater than distance Ll, and can be predetermined by design of extender <NUM> based on the desired distance D3, as shown in <FIG>.

Lower portion <NUM> can have an open interior portion <NUM> defined between first and second U-shaped sides <NUM> and <NUM>, and in which can be disposed an extender set screw <NUM>. Open interior portion <NUM> can have open access through a pair of opposing windows <NUM>, <NUM> (window <NUM> on the side not seen in <FIG>) through which the extender set screw <NUM> may be inserted into and then in its position therein, threads of extender set screw <NUM> can extend radially outwardly from windows <NUM>, <NUM>. That is, the outside thread diameter of set screw <NUM> can be greater than the protrusion width PW. This allows the threads of the extender set screw <NUM> to threadingly engage the inner threads <NUM> of the first and second tulip arms <NUM> when the lower portion <NUM> is inserted into the tulip channel <NUM>, engaging and/or connecting the extender <NUM> to the tulip head <NUM>. As can be understood from the description herein, extender set screw <NUM> serves functionally similar to the set screw <NUM> shown in <FIG> to set, however, the extender <NUM> into the tulip head <NUM> of pedicle screw <NUM> as shown in <FIG> rather than to set the rod <NUM> into the tulip head as shown in <FIG>.

An access opening <NUM> in upper portion <NUM> can extend downwardly through the upper portion <NUM> in a direction generally perpendicular to first channel axis <NUM>. Access opening <NUM> provides access to the top of extender set screw <NUM>. Extender set screw <NUM> can have on its top surface a driving portion which can engage with a driver to permit rotation of extender set screw <NUM> such that its external threads engage the internal threads <NUM> of tulip head <NUM>, driving the extender set screw down into the tulip channel <NUM> and connecting the extender <NUM> to the pedicle screw <NUM>.

Thus, according to the description above with reference to <FIG> and <FIG>, it can be understood that extender <NUM> can be attached to the tulip head <NUM> of a pedicle screw <NUM> to increase the distance from bone surface <NUM> from a distance having a dimension D1 to a distance having a dimension D3, which is greater than Dl. As described, the lower portion <NUM> of extender <NUM> can be positioned between the tulip arms <NUM> and the threads of extender set screw <NUM> can engage the interior threads <NUM> of tulip head <NUM>. Extender set screw <NUM> can be rotated by a driver extending through access opening <NUM> of extender <NUM> to connect and/or secure extender <NUM> to tulip head <NUM>. Once extender is secured to tulip head <NUM> by tightening extender set screw <NUM>, first and second extender arms <NUM> and <NUM>, first interior threads <NUM>, and interior channel <NUM> effectively define a second tulip head into which a spinal fixation rod <NUM> can be reduced. The distance having a dimension D2 above which a rod would be reduced into tulip head <NUM> of pedicle screw <NUM> can be predetermined by adjusting by design the various described components and dimensions. Thus, in operation, a doctor or other operator can choose an extender <NUM> having dimensions, including dimensions L1 and L2 for the particular pedicle screw <NUM> being utilized, and the distance D3 that the rod is suspended or positioned over the bone and/or the distance the rod is suspended and/or positioned over the installed pedicle screw. As can be understood, therefore, extender <NUM> provides great flexibility to increase the rod reduction height relative to bone surface <NUM> for a fixed position of a tulip head <NUM> of a fixed pedicle screw <NUM>.

An embodiment of tulip head extender <NUM> similar to that shown in <FIG> is depicted in more detail in <FIG>. <FIG> illustrates in a perspective view that extender <NUM> can comprise a one-piece molded body, forged and/or machined body, and, as shown in <FIG>, a set screw can be disposed internally to the extender <NUM> body. As an example, extender <NUM> is molded of any polymer material, and can be injection molded. As described above, extender <NUM> has an upper body portion <NUM> joined to a lower body portion <NUM>. Upper body portion <NUM> has two opposing extender arms <NUM>, <NUM>, each including a portion of interior threads <NUM>. First arm <NUM> and second arm <NUM> can extend from a curved lower surface defining a substantially U-shaped interior channel <NUM> that can have a first channel axis <NUM>. The first channel axis <NUM> can correspond to, and be coincident with, a longitudinal axis of a rod <NUM> when reduced into extender <NUM> (not shown). The first interior threads <NUM> of first and second arms can be complementary to receive an appropriately sized set screw <NUM>, as shown in <FIG>. An access opening <NUM> in upper portion <NUM> can extend downwardly through the upper portion <NUM> in a direction generally perpendicular to first channel axis <NUM>. Access opening <NUM> provides access to the top of extender set screw <NUM>. Extender set screw <NUM> can have on its top surface a driving portion <NUM> which can be a male or female socket that can engage with a driver to drive rotation of extender set screw <NUM>. In <FIG>, a representative female socket driving portion <NUM> having a generally star-shaped geometry is illustrated.

As can be understood from the description above, first and second extender arms <NUM> and <NUM>, first interior threads <NUM>, and interior channel <NUM> correspond to the same or similar functional features of a tulip head, such as tulip head <NUM> of pedicle screw <NUM>. As can be further understood, the features of the upper portion <NUM> of extender <NUM> can include any features <NUM> desired or required on illustrative bone anchors such as, for example, pockets, tabs, indentations, and openings, to engage with a variety of instruments such as, for example, a particular rod reducing tool, and, as such, facilitate rod reduction by known techniques, albeit reducing the rod a shorter distance than what would have been required to reduce it to the original rod seat <NUM>.

As shown in the side elevation views of <FIG> and <FIG>, lower portion <NUM> can extend downwardly from the upper portion <NUM>, and can have a portion sized to fit into the channel <NUM> and seat on the rod surface <NUM> of tulip head <NUM> of pedicle screw <NUM>. First and second U-shaped sides can be substantially identical in size and shape and have a protrusion width PW having a dimension sized according to the channel width of the tulip head <NUM> of the pedicle screw <NUM>. First and second U-shaped sides can be spaced apart a distance defining a protrusion depth PD, the protrusion depth PD being a dimension suitable for stable securement to the tulip head <NUM> of pedicle screw <NUM>, and can be predetermined based on the sizing and requirements of related instrumentation. First and second sides <NUM> and <NUM> need not be U-shaped, but can have any shape constrained only in that the lower portion <NUM> be able to be insertable into and seat with the tulip head <NUM> of a pedicle screw <NUM>. Thus, first and second sides <NUM> and <NUM> can have rectangular shape, for example, and remain functionally capable of being seated into the tulip head <NUM> of pedicle screw <NUM>.

The extender <NUM> can have first and second surfaces <NUM> and <NUM>, which can be generally horizontally oriented portions of the lower surface of upper portion <NUM>, and which can abut the top surface of tulip head <NUM> of pedicle screw <NUM> when the extender <NUM> is set into place. First and second sides <NUM> and <NUM> can extend a distance Ll below and generally perpendicular to first and second surfaces <NUM> and <NUM> to the bottom of the U-shaped sides. As discussed above with respect to <FIG>, but for conciseness not shown in <FIG>, a distance Ll can be substantially equal to the depth of the channel having the rod seat <NUM> of tulip head <NUM>. Curved lower surface <NUM> of upper portion <NUM> of extender <NUM> can be a distance L2 measured from the bottom of the U-shaped first and second sides <NUM> and <NUM>. Distance L2 can be greater than distance Ll, and can be predetermined by design of extender <NUM> based on the desired distance D3, as shown in <FIG>.

Lower portion <NUM> can have an open interior portion <NUM> defined between first and second U-shaped sides <NUM> and <NUM>, and in which can be disposed an extender set screw <NUM>. Open interior portion <NUM> can have open access through a pair of opposing windows <NUM>, <NUM> (window <NUM> on the side not seen in <FIG>) through which the extender set screw <NUM> may be inserted into and then, when in its position therein, threads of extender set screw <NUM> can extend radially outwardly from the windows <NUM>, <NUM>. That is, the outside thread diameter of set screw <NUM> can be greater than the protrusion width PW. This allows the threads of the extender set screw <NUM> to threadingly engage the inner threads <NUM> of the first and second tulip arms <NUM> when the lower portion <NUM> is inserted into the tulip channel <NUM>, engaging and/or connecting the extender <NUM> to the tulip head <NUM>. As can be understood from the description herein, extender set screw <NUM> serves functionally as the set screw <NUM> shown in <FIG> to set, however, the extender <NUM> into the tulip head <NUM> of pedicle screw <NUM> as shown in <FIG> rather than to set the rod <NUM> into the tulip head as shown in <FIG>.

<FIG> and <FIG> are partial cross-sectional views of <FIG> and <FIG> respectively and are provided for descriptive detail with respect to the various structure and features described above. For conciseness all the descriptive detail is not repeated, but the FIGS. can be understood by the description above and the various numbered call-outs of <FIG> and <FIG>.

Referring now to <FIG> there is shown another example of a tulip head extender <NUM> that, when installed onto tulip head <NUM>, can facilitate the repositioning of rod <NUM> with respect to bone surface <NUM> from a distance having a dimension D1 to an additional distance having a dimension D2, for a total distance having a dimension D3. As can be understood, extender <NUM> permits the vertical repositioning of rod <NUM> from an original position shown as <NUM> without disturbing the original position of pedicle screw <NUM>. The dimension D2 can be predetermined by varying the geometry of extender <NUM>, as will be more fully understood in light of the description below.

The example embodiment of extender <NUM> shown in <FIG> can have a rod securing body portion <NUM> having two opposing arms <NUM>, <NUM>, each including a portion of first interior threads <NUM>. First and second opposing arms can extend upwardly from a curved lower surface defining a substantially U-shaped interior channel <NUM> that can have a first channel axis <NUM>. First arm <NUM> and second arm <NUM> can be described as being opposed across a first imaginary plane P1 parallel to first channel axis <NUM> and bisecting the securing body portion <NUM>, and, when in use also bisecting tulip head <NUM> in a like manner.

Extender <NUM> can have generally parallel spaced apart first and second U-shaped sides, <NUM> and <NUM>. First and second U-shaped sides can be substantially identical in size and shape and have a separation width SW having a dimension sized according to the size of the tulip head <NUM> of the pedicle screw <NUM> over which extender <NUM> can be lowered and set, somewhat in saddle fashion. First and second sides <NUM> and <NUM> (opposite side of side <NUM>) can each have an externally facing surface that is generally planar and perpendicular to the imaginary plane P1. First and second sides <NUM> and <NUM> need not be U-shaped, but can have any shape constrained only by general design and function considerations. Thus, first and second sides <NUM> and <NUM> can have rectangular shape, for example, and remain functionally capable of being saddled over the tulip head <NUM> of pedicle screw <NUM>.

The first interior threads <NUM> of first and second arms can be complementary to receive an appropriately sized set screw (not shown). As can be understood from the description above, first and second arms <NUM> and <NUM>, first interior threads <NUM>, and interior channel <NUM> correspond to the same or similar functional features of a tulip head, such as tulip head <NUM> of pedicle screw <NUM>. As can be further understood, the features of the rod securing body <NUM> of extender <NUM> can include any features <NUM> desired or required on illustrative bone anchors such as, for example, pockets, tabs, indentations, and openings, to engage with a variety of instruments such as, for example, a particular rod reducing tool, and, as such, facilitate rod reduction as known, albeit reducing the rod a shorter distance than what would have been required to reduce it to the original rod seat as shown in <FIG>.

Rod securing body <NUM> can be secured to tulip head <NUM> in any suitable manner, for example, by securing to mating engagement portions. For example, rod securing body <NUM> can have tabs that can engage pockets <NUM> of tulip head <NUM>. In an example, tabs of rod securing body can be flexibly resilient, and can be separated apart while rod securing body is pressed down onto tulip head <NUM> and snapped inwardly when tabs engage pockets <NUM>. In another example, a first set screw can be, optionally, threadingly engaged to the internal extender threads <NUM> and threaded through the extender until it threadingly engages the internal threads <NUM> of tulip head <NUM>. The first set screw can be threaded into the tulip head to the desired position to secure and/or hold a spinal fixation rod <NUM> in position within the extender channel between the curved surface of the channel <NUM> and the first set screw, and at the same time, to hold and/or secure the extender <NUM> to tulip head <NUM>. Optionally, a second extender set screw (e.g., extender set screw <NUM>) can be threadingly engaged to the internal threads <NUM> of the extender <NUM> to provided additional hold and/or securement of the spinal fixation rod <NUM> to the extender. Rod securing body <NUM> can have generally flat, inwardly extending surfaces <NUM> that can abut the top surface of tulip head <NUM> when rod securing body is positioned for receiving a rod. Interior channel <NUM> can have a lower surface a distance having a dimension L3 above the lower surface of the extender <NUM>. Inwardly extending surfaces <NUM> can be disposed at a forth distance having a dimension L4 above the lower surface of extender <NUM>.

Once extender <NUM>, as described with reference to <FIG>, is secured to tulip head <NUM> by placing over the tulip head <NUM> in a saddle-like fashion, first and second arms <NUM> and <NUM>, first interior threads <NUM>, and interior channel <NUM> effectively define a second tulip head into which a rod <NUM> can be reduced. The dimension D2 above which a rod would be reduced into tulip head <NUM> of pedicle screw <NUM> can be predetermined by adjusting by design the various described components and dimensions. Thus, in operation, a doctor or other operator can choose an extender <NUM> having dimensions, including dimensions L3 and L4 for the particular pedicle screw <NUM> being utilized, and the desired dimension D3 for elevated rod reduction. As can be understood, therefore, extender <NUM> provides great flexibility to increase the rod reduction height relative to bone surface <NUM> for a fixed position of a tulip head <NUM> of a fixed pedicle screw <NUM>.

Thus, according to the description above with reference to <FIG>, it can be understood that in an example extender <NUM> can be attached to the tulip head <NUM> of a pedicle screw <NUM> to increase the distance from bone surface <NUM> from a first distance having a dimension D1 to a third distance having a dimension D3, which is greater than D <NUM>. Once extender <NUM> is secured to tulip head <NUM>, first and second arms <NUM> and <NUM>, first interior threads <NUM>, and interior channel <NUM> effectively define a second tulip head into which a rod <NUM> can be reduced. The second dimension D2 above which a rod would be reduced into tulip head <NUM> of pedicle screw <NUM> can be predetermined by adjusting by design the various described components and dimensions. Thus, in operation, a doctor or other operator, can choose an extender <NUM> having dimensions, including dimensions L3 and L4 for the particular pedicle screw <NUM> being utilized, and the desired dimension D3 for rod reduction. As can be understood, therefore, extender <NUM> provides great flexibility to increase the rod reduction height relative to bone surface <NUM> for a fixed position of a tulip head <NUM> of a fixed pedicle screw <NUM>.

Referring now to <FIG>, there is shown another example of a tulip head extender <NUM> that, when installed onto tulip head <NUM>, can facilitate the repositioning of rod <NUM> with respect to bone surface <NUM> from a distance having a dimension D1 to an additional distance having a dimension D2, for a total distance having a dimension D3 (as depicted in <FIG>). As can be understood by the description herein, extender <NUM> permits the vertical repositioning of rod <NUM> without disturbing the original position of a pedicle screw <NUM>. The dimension D2 can be predetermined by varying the geometry of extender <NUM>, as will be more fully understood in light of the description below.

As shown in the example of <FIG>, extender <NUM> can comprise three discrete parts that together serve to fix a spinal fixation rod <NUM> on a pedicle screw head <NUM> at an elevated distance from the bone in which pedicle screw is affixed. <FIG> shows a perspective view of an extender <NUM> comprising three discrete parts, namely a saddle <NUM>, a cap <NUM>, and a set screw <NUM>, which can be in all respects identical to the set screw <NUM> described above. All three parts can be made of any suitable material, including injection molded polymer materials.

Referring to <FIG>, saddle <NUM> can be disposed within the tulip head <NUM> of a pedicle screw (i.e., within channel <NUM>). Saddle <NUM> can be slid into the tulip head <NUM> and can rest on the rod seat <NUM>. Saddle <NUM> can have on the upper, rod-facing side a surface that defines an elevated rod seat <NUM>. Saddle <NUM> is described in more detail with respect to <FIG>.

Referring to <FIG>, a cap <NUM> can be snapped onto tulip head <NUM>, for example, by utilizing tabs <NUM> that can clip onto pockets <NUM> of tulip head <NUM>. One tab <NUM> can be hooked into one pocket <NUM>, and the cap <NUM> can be rotated and pressed such that the other tab <NUM> can be hooked, or snapped, into the opposite pocket <NUM>. In other words, the tabs <NUM> can be fabricated from a material and/or by design such that one or more of the tabs <NUM> can flex outward to go over and/or about the outer circumference of the tulip head and then snap back into its normal position into one or more of the pockets <NUM>. Once snapped onto tulip head <NUM>, cap <NUM> is secured onto tulip head <NUM> as shown in <FIG>. A spinal fixation rod <NUM> may be positioned into the saddle prior to the cap <NUM> being positioned upon and secured to the tulip head, thus positioning the rod <NUM> between the saddle and the cap. Once positioned, the set screw <NUM> may be threadingly engaged to the tulip head <NUM> and/or the cap <NUM>. Alternatively, once the saddle <NUM> and cap <NUM> are positioned onto the tulip head <NUM>, a spinal fixation rod <NUM> can be positioned between them, and secured to the tulip head <NUM> by inserting and securing a set screw <NUM>, as shown in <FIG> (i.e., threadingly engaged to the tulip head <NUM> and/or the cap <NUM>).

A schematic perspective view of the extender <NUM> shown in <FIG> is depicted in <FIG>. Once extender <NUM>, as described with reference to <FIG>, is secured to a pedicle screw head <NUM> having a rod seat <NUM> at an elevation D1 above the bone surface, the elevated rod seat <NUM>' can be elevated above the rod seat <NUM> by a distance having a dimension D2 which can be predetermined by adjusting by design the various described components and dimensions. Thus, in operation, a doctor or other operator can choose an saddle <NUM> having dimensions, specifically a saddle height dimension as discussed below, for the particular pedicle screw <NUM> being utilized, and the desired dimension D3 for elevated rod reduction. As can be understood, therefore, extender <NUM> provides great flexibility to increase the rod reduction height relative to bone surface <NUM> for a fixed position of a tulip head <NUM> of a fixed pedicle screw <NUM>.

<FIG> shows a perspective view of a representative saddle <NUM> used in the extender <NUM> shown in <FIG>. In particular, saddle <NUM> can be generally H-shaped having a longitudinally extending curved surface <NUM> that serves as the elevated rod seat <NUM>. A pair of opposing guide tabs <NUM> can be disposed at each longitudinal end of the curved surface <NUM>. The size and spacing of tabs <NUM> can be predetermined according to the dimensions of the tulip head <NUM> onto which saddle <NUM> is placed. Saddle <NUM> can have a thickness from a bottom surface to a top surface of the elevated rod seat <NUM>' SH, as shown in <FIG>. The saddle height SH can be predetermined for the desired dimension D3 for elevated rod reduction.

Referring to <FIG>, there is shown a perspective view of cap <NUM>. Cap <NUM> can have two opposed tabs <NUM> that can have a general hook-shape such that a first tab <NUM>' with a hook feature <NUM>' that can engage with a pocket <NUM> of tulip head <NUM>, as illustrated above with respect to <FIG>. A second tab <NUM>" with a second hook feature <NUM>" can be pressed down and snapped into a pocket <NUM> on the opposite side of a tulip head <NUM>. A stress relief feature <NUM>, which can include a slot <NUM> and/or a slit <NUM> on the upper portion of cap <NUM>, from which tabs <NUM> extend downwardly, can be included on cap <NUM>. Cap <NUM> can also have indented features, such as a pocket <NUM>' on opposite side surfaces of cap <NUM>. Pockets <NUM>' provide a connection for connectivity and operation of known instruments such as, for example, a driving tool and/or rod reducing tool.

Referring to <FIG> there is illustrated in perspective a set screw <NUM> having external threads that engage with the internal threads of the tulip head of a pedicle screw, or other internal threads of extenders <NUM> as described herein. Set screw <NUM> can be turned by a tool that can be inserted into a driving portion <NUM> that can be a socket into which a driving tool can be inserted and securely rotated to rotate set screw <NUM>.

Referring to <FIG> there is illustrated further examples of extenders <NUM> that facilitate positioning of a spinal fixation rod <NUM> both laterally and upwardly with respect to a fixed pedicle screw <NUM> tulip head <NUM>. <FIG> and <FIG> illustrate an extender <NUM> that facilitates laterally elevated in-line positioning of rod <NUM>. <FIG> and <FIG> illustrate an extender <NUM> that facilitates laterally elevated cross positioning of rod <NUM>.

As shown in <FIG>, an extender <NUM> is illustrated that permits a rod <NUM> to be reduced to an elevation greater than the elevation dictated by a pedicle screw <NUM> fixed in a bone <NUM>. As shown in <FIG> and <FIG>, extender <NUM> can be a unitary construction, and can have a mounting bar <NUM> that can be cylindrical, and can be sized to fit and be secured into tulip head <NUM> of fixed pedicle screw <NUM>. Securement of mounting bar <NUM> into tulip head <NUM> can be, for example, by a set screw (not shown) tightened into internal threads <NUM> of tulip head <NUM>. Mounting bar can have any cross section, but can be a cylindrical shape having a central axis <NUM>.

Extender <NUM> as illustrated in <FIG> and <FIG> can have disposed on an upturned end of mounting bar <NUM> an extender tulip head <NUM> that can be in size, shape, and function, substantially identical to tulip head <NUM> of pedicle screw <NUM>. In general, extender tulip head <NUM> can have two opposing arms <NUM>, <NUM>, each including a portion of interior threads <NUM>. First arm <NUM> and second arm <NUM> can extend from a curved lower surface defining a substantially U-shaped interior channel <NUM> that can have a first channel axis <NUM> can be coincident with the central axis of rod <NUM> and can be generally parallel to and in the same plane as central axis <NUM>. The first interior threads <NUM> of first and second arms can be complementary to receive an appropriately sized set screw (not shown). As can be understood from the description herein, first and second arms <NUM> and <NUM>, first interior threads <NUM>, and interior channel <NUM> correspond to the functional features of a tulip head, such as tulip head <NUM> of pedicle screw <NUM>. As can be further understood, the features of the extender tulip head <NUM> can include any features required (but not shown) to engage with a particular rod reducing tool, and, as such, facilitate rod reduction as known, albeit reducing the rod to distance having a dimension D3 rather than distance a lesser dimension D1, as shown in <FIG>.

In the example illustrated in <FIG> and <FIG>, the first channel axis <NUM> and the central rod axis <NUM> of mounting bar <NUM> are parallel and in the same plane, and thus a fixation rod <NUM> reduced into extender tulip head <NUM> is "in line" with the mounting bar <NUM>, and thus in line directionally with where the fixation rod <NUM> would have been mounted in the tulip head <NUM> of pedicle screw <NUM>.

As can be understood with respect to <FIG> and <FIG>, an example of another extender <NUM> that facilitates fixation of a rod <NUM> both laterally and upwardly with respect to a fixed pedicle screw <NUM> tulip head <NUM> is shown. The extender of <FIG> and <FIG> is identical in most respects to that shown in <FIG> and <FIG>, with the material difference being that extender tulip head <NUM> has a different orientation, such that a rod <NUM> reduced into it would not be "in line" with mounting bar, but be at some angle to it, albeit remaining elevated by distance having a dimension D2 with respect to the mounting bar. In an example, first arm <NUM> and second arm <NUM> can extend from a curved lower surface defining a substantially U-shaped interior channel <NUM> that can have a first channel axis <NUM> that is generally parallel to but in different plane than central axis <NUM>. In an example, first channel axis <NUM> can be in a plane that is substantially perpendicular to a plane in which central axis <NUM> resides. However, in general, as described above, the first interior threads <NUM> of first and second arms can be complementary to receive an appropriately sized set screw (not shown). As can be understood from the description herein, first and second arms <NUM> and <NUM>, first interior threads <NUM>, and interior channel <NUM> correspond to the functional features of a tulip head, such as tulip head <NUM> of pedicle screw <NUM>. As can be further understood, the features of the extender tulip head <NUM> can include any features required (but not shown) to engage with a particular rod reducing tool, and, as such, facilitate rod reduction as known, albeit reducing the rod to distance to a dimension D3 rather than to a distance having a dimension D1 which is less than D3, as shown in <FIG>.

As depicted in <FIG> dimension D3 can be varied depending on the dimensions of extender <NUM>, specifically the distance which can be measured from mounting bar axis <NUM> and a lower surface <NUM> of head <NUM>, which distance can be the dimension L5. More particularly, dimension D3 can be varied depending on the distance which can be measured from mounting bar axis <NUM> and a rod seating surface <NUM> of head <NUM>, which distance can be the dimension L6.

The extenders <NUM> disclosed herein can provide a benefit in the installation and use of spinal fixation rods. In general, a method of use of extender <NUM> includes affixing an extender <NUM> to an installed tulip head of a pedicle screw, thereby extending, with respect to the pedicle bone, the distance from the pedicle bone that a spinal fixation rod will seat. In general, an extender <NUM> can safely span a gap between the distance from the pedicle bone of the rod seat <NUM> of a tulip head <NUM> of an installed pedicle screw and the distance that is determined as safely seating a spinal fixation rod.

For extenders <NUM> of the type illustrated and disclosed, for example, with respect to <FIG>, the extender <NUM> can have a set screw, e.g., set screw <NUM> of <FIG> and <FIG>, threaded through the extender <NUM> and threaded onto the internal threads <NUM> of the tulip head <NUM>, thereby securing the extender <NUM> to the tulip head <NUM>. After the extender <NUM> is secured to the tulip head <NUM>, a spinal fixation rod <NUM> can be seated in the extender and secured, e.g., with another set screw threaded into first interior threads <NUM> as depicted in <FIG>.

For extenders <NUM> of the type illustrated and disclosed, for example, with respect to <FIG>, the saddle <NUM> provides for the extended distance with respect to the pedicle bone, i.e., the distance from the pedicle bone that a spinal fixation rod will seat. The cap <NUM> can then be snapped over the top of the tulip head into the slots on the side thereof. A set screw can then be tightened down, thereby pulling the cap <NUM> upward on the slots locking it in place.

The apparatuses and methods disclosed herein may be used and/or applied in any regions of the spine such as for example, cervical, thoracic, lumbar, sacral, or coccygeal regions. In some examples, the apparatuses and methods disclosed herein may be used and/or applied in severely curved regions of the spine, for example, the lumbar region of the spine, i.e., for a spinal fixation rod secured to any or all of Ll-L5 vertebrae. The lumbar region can often exhibit extreme lumbar curves where a spinal fixation rod would necessarily need to be significantly deformed, thus creating large stresses in the rod and/or the pedicle screw and/or the bone, as well as possible fracture of either the rod, screw, or bone. Extenders <NUM> can also be used in other vertebrae, including, for example, in the upper thoracic region for severe kyphosis, i.e., for a spinal fixation rod secured to any or all of T1 -T12 vertebrae, where there can also be significantly rod stresses present. Extenders <NUM> can also be used in vertebrae of the cervical region, i.e., for a spinal fixation rod secured to any or all of C1-C7.

Representative examples of the present disclosure described above can be described as follows.

In a non-claimed example of a method of use can include the following steps: inserting a pedicle screw having a tulip head in a vertebral bone to a predetermined distance; placing a spinal fixation rod in close proximity to, e.g., hovering over, the tulip head of the inserted pedicle screw; determining that the distance the spinal fixation rod must be reduced into the tulip head is too great to allow for safe reduction of the spinal fixation rod into the tulip head, e.g., because of the likelihood of excessive stress on the pedicle bone; securing an extender <NUM> to the tulip head of the pedicle screw; seating the spinal fixation rod into the extender <NUM>; and securing the spinal fixation rod into the extender <NUM>.

A method of use for extenders as described above can be described as a method for securing a spinal fixation rod to a pedicle bone, the method including the following steps: providing a tulip head of a pedicle screw; providing a spinal fixation rod; securing an extender <NUM> to the tulip head of the pedicle screw; seating the spinal fixation rod into the extender <NUM>; and securing the spinal fixation rod into the extender <NUM>.

A method of use for extenders as described above can be described as a method for securing a spinal fixation rod to a pedicle bone, the method including the following steps: providing a tulip head of a pedicle screw screwed into a pedicle bone; providing a spinal fixation rod; securing an extender <NUM> to the tulip head of the pedicle screw; seating the spinal fixation rod into the extender <NUM>; and securing the spinal fixation rod into the extender <NUM>.

A method of use for extenders as described above can be described as a method for securing a spinal fixation rod to a pedicle bone, the method including the following steps: providing a plurality of pedicle screws each comprising a tulip head, and each screwed into a respective pedicle bone; securing at least one extender <NUM> to the tulip head of at least one of the tulip heads of at least one of the pedicle screws; bending a spinal fixation rod to an approximate shape; seating the bent spinal fixation rod into the at least one extender <NUM>; and securing the spinal fixation rod into the at least one extender <NUM>.

A method of use for extenders as described above can be described as a method for securing a spinal fixation rod to a pedicle bone, the method including the following steps: providing a plurality of pedicle screws each comprising a tulip head, and each screwed into a respective pedicle bone; recognizing that the required shape of an attached spinal fixation rod will exert excessive stress on the pedicle bone; securing at least one extender <NUM> to the tulip head of at least one of the tulip heads of at least one of the plurality of pedicle screws; bending a spinal fixation rod to an approximate shape; seating the bent spinal fixation rod into the at least one extender <NUM>; and securing the spinal fixation rod into the at least one extender <NUM>.

A method of use for extenders as described above can be described as a method for securing a spinal fixation rod to a pedicle bone, the method including the following steps: on the spine of a patient in need of orthopedic surgery, providing a plurality of pedicle screws each comprising a tulip head, and each screwed into a respective pedicle bone of the spine; recognizing that the required shape of an attached spinal fixation rod exerts excessive stress on the pedicle bone; securing at least one extender <NUM> to at least one of the tulip heads of at least one of the plurality of pedicle screws; bending a spinal fixation rod to an approximate shape; seating the bent spinal fixation rod into the at least one extender <NUM>; and securing the spinal fixation rod into the at least one extender <NUM>.

A method of use for extenders as described above can be described as a method for securing a spinal fixation rod to a pedicle bone, the method including the following steps: on the lumbar region of a spine of a patient in need of orthopedic surgery, providing a plurality of pedicle screws each comprising a tulip head, and each screwed into a respective pedicle bone of the spine selected from the group consisting of L1-L5; recognizing that the required shape of an attached spinal fixation rod exerts excessive stress on the pedicle bone or the pedicle screw; securing at least one extender <NUM> to at least one of the tulip heads of at least one of the plurality of pedicle screws; bending a spinal fixation rod to an approximate shape; seating the bent spinal fixation rod into the at least one extender <NUM>; and securing the spinal fixation rod into the at least one extender <NUM> in the lumbar region of the spine.

A method of use for extenders as described above can be described as a method for securing a spinal fixation rod to a pedicle bone, the method including the following steps: on the cervical region of a spine of a patient in need of orthopedic surgery, providing a plurality of pedicle screws each comprising a tulip head, and each screwed into a respective pedicle bone of the spine selected from the group consisting of C <NUM> -C7; recognizing that the required shape of an attached spinal fixation rod exerts excessive stress on the pedicle bone or the pedicle screw; securing at least one extender <NUM> to at least one of the tulip heads of at least one of the plurality of pedicle screws; bending a spinal fixation rod to an approximate shape; seating the bent spinal fixation rod into the at least one extender <NUM>; and securing the spinal fixation rod into the at least one extender <NUM> in the cervical region of the spine.

A method of use for extenders as described above can be described as a method for securing a spinal fixation rod to a pedicle bone, the method including the following steps: on the thoracic region of a spine of a patient in need of orthopedic surgery, providing a plurality of pedicle screws each comprising a tulip head, and each screwed into a respective pedicle bone of the spine selected from the group consisting of T <NUM> -T12; recognizing that the required shape of an attached spinal fixation rod exerts excessive stress on the pedicle bone or the pedicle screw; securing at least one extender <NUM> to at least one of the tulip heads of at least one of the plurality of pedicle screws; bending a spinal fixation rod to an approximate shape; seating the bent spinal fixation rod into the at least one extender <NUM>; and securing the spinal fixation rod into the at least one extender <NUM> in the thoracic region of the spine.

A method of use for extenders as described above can be described as a method for repositioning and securing a spinal fixation rod to a pedicle bone, the method including the following steps: on the lumbar region of a spine of a patient in need of orthopedic surgery, providing a plurality of pedicle screws, each of the pedicle screws comprising a tulip head, and each screwed into a respective pedicle bone of the spine selected from the group consisting of L1-L5; seating a spinal fixation rod into a portion of the tulip heads; recognizing that the required shape of the spinal fixation rod exerts, or will exert, excessive stress on the pedicle bone or the pedicle screw; removing the spinal fixation rod from the portion of the tulip heads; securing at least one extender <NUM> to at least one of the tulip heads of at least one of the plurality of pedicle screws; re-seating the spinal fixation rod to into the portion of tulip heads, including the at least one extender <NUM>; and securing the spinal fixation rod into the tulip heads, including the at least one extender <NUM>, in the lumbar region of the spine. For each of the methods of use described above involving bending a spinal fixation rod prior to it being secured to an extender <NUM>, the shape of the relevant portion of the spinal fixation rod <NUM>, i.e., at and near the extender <NUM>, can be characterized as wherein the radius of curvature of the bend in the spinal fixation rod is greater when used with an extender <NUM> relative to the radius of curvature necessary without the use of an extender <NUM>.

A method of use for extenders as described above can be described as a method for repositioning and securing a spinal fixation rod to a pedicle bone, the method including the following steps: on the cervical region of a spine of a patient in need of orthopedic surgery, providing a plurality of pedicle screws, each of the pedicle screws comprising a tulip head, and each screwed into a respective pedicle bone of the spine selected from the group consisting of Cl-C7; seating a spinal fixation rod into a portion of the tulip heads; recognizing that the required shape of the spinal fixation rod exerts, or will exert, excessive stress on the pedicle bone or the pedicle screw; removing the spinal fixation rod from the portion of the tulip heads; securing at least one extender <NUM> to at least one of the tulip heads of at least one of the plurality of pedicle screws; re-seating the spinal fixation rod to into the portion of tulip heads, including the at least one extender <NUM>; and securing the spinal fixation rod into the tulip heads, including the at least one extender <NUM>, in the cervical region of the spine. For each of the methods of use described above involving bending a spinal fixation rod prior to it being secured to an extender <NUM>, the shape of the relevant portion of the spinal fixation rod <NUM>, i.e., at and near the extender <NUM>, can be characterized as wherein the radius of curvature of the bend in the spinal fixation rod is greater when used with an extender <NUM> relative to the radius of curvature necessary without the use of an extender <NUM>.

A method of use for extenders as described above can be described as a method for repositioning and securing a spinal fixation rod to a pedicle bone, the method including the following steps: on the thoracic region of a spine of a patient in need of orthopedic surgery, providing a plurality of pedicle screws, each of the pedicle screws comprising a tulip head, and each screwed into a respective pedicle bone of the spine selected from the group consisting of T1-T12; seating a spinal fixation rod into a portion of the tulip heads; recognizing that the required shape of the spinal fixation rod exerts, or will exert, excessive stress on the pedicle bone or the pedicle screw; removing the spinal fixation rod from the portion of the tulip heads; securing at least one extender <NUM> to at least one of the tulip heads of at least one of the plurality of pedicle screws; re-seating the spinal fixation rod to into the portion of tulip heads, including the at least one extender <NUM>; and securing the spinal fixation rod into the tulip heads, including the at least one extender <NUM>, in the thoracic region of the spine. For each of the methods of use described above involving bending a spinal fixation rod prior to it being secured to an extender <NUM>, the shape of the relevant portion of the spinal fixation rod <NUM>, i.e., the at and near the extender <NUM>, can be characterized as wherein the radius of curvature of the bend in the spinal fixation rod is greater when used with an extender <NUM> relative to the radius of curvature necessary without the use of an extender <NUM>.

A non-claimed method for securing a spinal fixation rod to a pedicle bone in the lumbar region of a spine of a patient in need of orthopedic surgery to modify the curvature of the lumbar region, the method including the following steps: providing a plurality of pedicle screws, at least one of the pedicle screws comprising a tulip head, and each screwed into a respective pedicle of a vertebrae of the spine selected from the group consisting of L1-L5; providing a pedicle screw extender; reducing a spinal fixation rod at least partially into the tulip head; recognizing that upon full reduction and securing of the spinal fixation rod into the tulip head the spinal fixation rod will exert excessive stress on the respective vertebra; removing the spinal fixation rod from the tulip head; securing the pedicle screw extender to the tulip head; re-reducing the spinal fixation rod into the pedicle screw extender; and securing the spinal fixation rod into the pedicle screw extender.

A non-claimed method for securing a spinal fixation rod to a pedicle bone of a spine of a patient in need of orthopedic surgery to modify the curvature of the spine, the method including the following steps: providing a tulip head of a pedicle screw; providing a pedicle screw extender; providing a spinal fixation rod; securing the pedicle screw extender to the tulip head of the pedicle screw; seating the spinal fixation rod into the pedicle screw extender; and securing the spinal fixation rod into the pedicle screw extender.

A non-claimed method for securing a spinal fixation rod to a pedicle bone on the lumbar region of a spine of a patient in need of orthopedic surgery to modify the curvature of the lumbar region, the method including the following steps: providing a pedicle screw comprising a tulip head, the pedicle screw being screwed into a pedicle bone of a vertebrae of the spine selected from the group consisting of L1-L5; providing a pedicle screw extender; recognizing that the required shape of an attached spinal fixation rod exerts excessive stress on the pedicle bone; securing the pedicle screw extender to the tulip head of the pedicle screw; bending a spinal fixation rod to an approximate desired curvature of the lumbar region; seating the spinal fixation rod into the pedicle screw extender; and securing the spinal fixation rod into the pedicle screw extender.

The method wherein the pedicle screw extender comprises: an upper body portion joined to a lower body portion, the upper body portion having two opposing arms extending upwardly from a curved lower surface to define a substantially U-shaped interior channel having a first channel axis, the curved lower surface defining an access opening extending through the upper body portion in a direction generally perpendicular to the first channel axis, the lower body portion extending downwardly as a protrusion from the upper body portion and joined to the upper body portion and having first and second sides, the first and second sides being substantially planar and parallel and separated by an interior portion, the first and second sides defining a protrusion height and a protrusion width, and a screw disposed in the interior portion and having external threads defining a thread diameter greater than the protrusion width.

The foregoing description of embodiments and examples has been presented for purposes of illustration and description.

Claim 1:
A pedicle screw tulip head extender (<NUM>), the tulip head extender (<NUM>) allowing vertical repositioning of a rod (<NUM>) with respect to a bone surface (<NUM>) when engaged to and/or installed into a U-shaped interior channel (<NUM>) formed by opposed first and second tulip arms (<NUM>) of a tulip head (<NUM>) of a pedicle screw (<NUM>), the tulip head extender (<NUM>) comprising:
a body having an upper body portion (<NUM>) joined to a lower body portion (<NUM>), wherein the upper body portion (<NUM>) is either integrally formed with lower body portion (<NUM>) by machining from a blank, injection molding, or the like, or the upper body portion (<NUM>) and the lower body portion (<NUM>) are formed separately and joined by adhesive, welding, press fit, or the like
i. the upper body portion having two opposing arms (<NUM>, <NUM>) extending upwardly from a curved lower surface to define a substantially U-shaped interior channel (<NUM>) having a first channel axis (<NUM>) that is coincident with a longitudinal axis of the rod (<NUM>) when reduced into the extender (<NUM>), the curved lower surface defining an access opening (<NUM>) extending through the upper body portion in a direction generally perpendicular to the first channel axis,
ii. the lower body portion extending downwardly as a protrusion from the upper body portion and joined to the upper body portion and having first and second sides (<NUM>, <NUM>),
characterized in that
the first and second sides being substantially planar and parallel and separated by an open interior portion (<NUM>), the first and second sides defining a protrusion depth (PD) and a protrusion width (PW),
and by
iii. an extender set screw (<NUM>) disposed in the open interior portion (<NUM>) and having external threads defining a thread diameter greater than the protrusion width (PW) allowing the threads of the extender set screw (<NUM>) to threadingly engage inner threads (<NUM>) of the tulip head (<NUM>) of the pedicle screw (<NUM>) to connect and/or secure the extender (<NUM>) to the tulip head (<NUM>).