Patent ID: 12185985

DETAILED DESCRIPTION

Spinal instrumentation is used to stabilize the spine for spinal fusion operations. Such spinal instrumentation can include a spinal rod which is secured to one or more vertebrae via pedicle screws. Adjacent segment deterioration can occur above or below an instrumented spinal fusion, necessitating more surgery and an overall longer spinal rod. Removing an existing spinal rod and replacing it with another, longer spinal rod is a highly invasive procedure. However, it can be difficult to link in to existing pedicle screw and spinal rod instrumentation, especially when the subsequent surgery is done in a minimally invasive manner through small incisions. Existing devices attempt to allow for minimally invasive spinal rod extensions, but all of the existing mechanisms are designed to bypass the existing pedicle screw heads at the top or bottom of a construct. This makes the connecting device bulky, which can lead to potential complications and/or patient discomfort.

Described herein are spinal rod extensions that allow for minimally invasive surgery, while providing a low profile design that minimizes the bulk of the extension. Specifically, the spinal rod extensions described herein go through existing pedicle screw heads instead of bypassing them.FIG.1is a side view of a spinal rod extension100in accordance with an illustrative embodiment. The spinal rod extension is a single piece but has three main features or sections. Sections105and110are designed to attach to an existing spinal rod (not shown), and section115(also referred to herein as a rod portion) is the extended length of rod that will attach to new pedicle screws (not shown). Section105(also referred to herein as a connector portion) has a curved undersurface (not shown) that fits onto the top of an existing spinal rod (not shown), and section110comprises a lip or an opening that accommodates the end of an existing spinal rod, thus enabling mating of the spinal rod extension to an existing spinal rod. In an alternative embodiment, spinal rod extension100can be comprised of two or more pieces, with a hinge or other articulation connecting section110(which is a single unit with section105) to section115.

FIG.2is an angled view of a spinal rod extension100in accordance with an illustrative embodiment. Section105has a curved undersurface120that fits onto the top of an existing spinal rod (not shown) and section110comprises an opening that accommodates the end of an existing spinal rod (not shown), thus enabling mating of the spinal rod extension to an existing spinal rod (not shown). Section110can partially or fully surround the existing spinal rod, depending on the implementation. Section115is the extended length of rod that will attach to new pedicle screws (not shown).

FIG.3is a side view of an existing two-level pedicle screw instrumentation construct300, in accordance with an illustrative embodiment. The pedicle screw instrumentation construct depicted here would span two intervertebral disk levels while performing a two-level instrumented spinal fusion and includes an existing spinal rod320attached to three pedicle screws305,306, and307. The pedicle screws305,306, and307are comprised of a threaded shaft315that in practice would be screwed into a vertebra of a patient (not shown) and a head310,311, and312that accommodates the existing spinal rod320.

FIG.4is an angled view of an existing two-level pedicle screw instrumentation construct300, in accordance with an illustrative embodiment. The pedicle screw instrumentation construct depicted here would span two intervertebral disk levels while performing a two-level instrumented spinal fusion and includes an existing spinal rod320attached to three pedicle screws305,306, and307. The pedicle screws are comprised of a threaded shaft315that would be screwed into a vertebra of a patient (not shown) and a u-shaped head310,311, and312that is configured to receive the existing spinal rod320. Depending on the implementation, a u-shaped head310,311, and312may be pivotally mounted to the threaded shaft315of the pedicle screw. At least an upper portion of the u-shaped head310,311, and312is threaded and configured to receive a locking cap325,330, and335. The locking cap may be alternatively referred to as a set screw. The existing spinal rod320is secured to the pedicle screws by locking caps (or alternatively called set screws)325,330, and335. The locking caps325,330, and335are used to secure the existing spinal rod320such that it remains within the u-shaped head310,311, and312of the pedicle screw305,306, and307.

FIG.5is an angled view of a spinal rod extension100and an existing two-level pedicle screw instrumentation construct300, in accordance with an illustrative embodiment. Locking cap325has been removed from pedicle screw head310of pedicle screw305in order to create space for the spinal rod extension100to mate to existing spinal rod320. Pedicle screws306and307have the locking caps330and335still engaged to pedicle screw heads311and312, thus continuing to attach to rod320.

FIG.6is an angled view of a spinal rod extension100and an existing two-level pedicle screw instrumentation construct300, in accordance with an illustrative embodiment. Locking cap325has been removed from pedicle screw head310of pedicle screw305in order to create space for the spinal rod extension100to mate to existing spinal rod320. Pedicle screws306and307have the locking caps330and335still engaged to pedicle screw heads311and312, thus continuing to attach to rod320.

The spinal rod extension100can be used to extend the existing spinal rod320in the event that the patient with the existing spinal rod320needs additional surgery to correct and/or fuse one or more adjacent vertebrae. The spinal rod extension100includes a connector portion comprised of an opening110which is configured to mate with at least a portion of the terminal end of the existing spinal rod320and a section105that rests on top of the existing spinal rod and fits intimately by virtue of a concave undersurface120that mates with the convex surface of existing spinal rod320. The spinal rod extension100also includes a rod portion115that can be used to lengthen the existing spinal rod320. In an illustrative embodiment, the rod portion115and the connector portions105and110can be molded together or manufactured as a single piece with the rod portion115and the connector portions105and110having various lengths. In an alternative embodiment, the rod portion115may be detachably mounted to the connector portion110. In such an embodiment, prior to or during surgery, the surgeon can select a rod portion115of appropriate length and mount it to the connector portion110. The mounting can be performed via one or more of a fastener, clamp(s), male/female connection, etc. In another embodiment, the rod portion115may articulate relative to the connector portion110.

In use, the set screw325is removed such that the connector portion105of the spinal rod extension100can be inserted through the u-shaped head310of the pedicle screw305that was used in the original surgery to secure the existing spinal rod320. In an illustrative embodiment, a bottom portion (in accordance with the orientation depicted inFIG.2) of the connector portion105can be curved or concave such that the connector portion105form-fits the convex contour of the existing spinal rod320. As such, when mounted to the existing spinal rod320, the connector portion105can be flush with or within a top edge of the u-shaped head310. In an alternative embodiment, the connector portion105may extend slightly beyond the top edge of the u-shaped head310.

In at least some embodiments, the spinal rod extension100includes an opening110with a lip111that is configured to mate with at least a portion of the terminal end of the existing spinal rod320and help secure the spinal rod extension100to the existing spinal rod320. In one embodiment, the lip111can be configured to engage just a bottom portion of the existing spinal rod320that extends past the u-shaped head310of the pedicle screw305. Alternatively, the lip111can form a circular (i.e., rod-shaped) opening110that is configured to receive the entire end of the existing spinal rod320that extends past the u-shaped head310of the pedicle screw305and form a male/female connection between the existing spinal rod320and the spinal rod extension100.

FIG.7is a side view of a spinal rod extension100mated to an existing spinal rod320of an existing two-level pedicle screw instrumentation construct300, in accordance with an illustrative embodiment. Locking cap325has been removed from pedicle screw head310of pedicle screw305, and section105of spinal rod extension100passes through screw head310in the region previously occupied by locking cap325and is seated on existing spinal rod320. Section110of spinal rod extension100fits around the end of existing spinal rod320in a male-female connection configuration, and the extension section115of spinal rod extension100is available to be secured to new pedicle screws (not shown). Pedicle screws306and307have the locking caps still engaged to pedicle screw heads311and312, thus continuing to attach to the existing spinal rod320.

FIG.8is an angled view of a spinal rod extension100mated to an existing spinal rod320of an existing two-level pedicle screw instrumentation construct300, in accordance with an illustrative embodiment. Locking cap325has been removed from pedicle screw head310of pedicle screw305, and section105of spinal rod extension100passes through screw head310in the region previously occupied by locking cap325and is seated on existing spinal rod320. Section110of spinal rod extension100fits around the end of existing spinal rod320, and the extension section115of spinal rod extension100is available to be secured to new pedicle screws (not shown). Pedicle screws306and307have the locking caps330and335still engaged to pedicle screw heads311and312, thus continuing to attach pedicle screws306and307to the existing spinal rod320.

FIG.9is a top view of a spinal rod extension100mated to an existing spinal rod320of an existing two-level pedicle screw instrumentation construct300, in accordance with an illustrative embodiment. Locking cap325(shown inFIG.8but no longer shown inFIG.9) has been removed from pedicle screw head310of pedicle screw305, and section105of spinal rod extension100passes through screw head310in the region previously occupied by locking cap325and is seated on existing spinal rod320. Section110of spinal rod extension100fits around the end of existing spinal rod320, and the extension section115of spinal rod extension100is available to be secured to new pedicle screws (not shown). Pedicle screws306and307have the locking caps330and335still engaged to pedicle screw heads311and312, thus continuing to attach pedicle screws306and307to the existing spinal rod320.

FIG.10is a cross-sectional side view of a spinal rod extension100and an existing spinal rod320of an existing two-level pedicle screw instrumentation construct300, in accordance with an illustrative embodiment. Section110of spinal rod extension100fits around the end of existing spinal rod320, and the extension section115of spinal rod extension100is available to be secured to new pedicle screws (not shown). Pedicle screws306and307would have the locking caps330and335(shown inFIG.8, not shown here) still engaged to pedicle screw heads311and312, thus continuing to attach pedicle screws306and307to the existing spinal rod320. The threaded shafts315of the pedicle screws305,306, and307are shown. Locking cap325(shown inFIG.8but no longer shown inFIG.10) has been removed from pedicle screw head310of pedicle screw305, and section105of spinal rod extension100passes through screw head310in the region previously occupied by locking cap325and is seated on existing spinal rod320.

FIG.11is a cross-sectional side view of a spinal rod extension100mated to an existing spinal rod320of an existing two-level pedicle screw instrumentation construct300, in accordance with an illustrative embodiment. Section110of spinal rod extension100fits around the end of existing spinal rod320, and the extension section115of spinal rod extension100is available to be secured to new pedicle screws (not shown). Locking cap325(shown inFIG.8but no longer shown here) has been removed from pedicle screw head310of pedicle screw305, and section105of spinal rod extension100passes through screw head310in the region previously occupied by locking cap325and is seated on existing spinal rod320. Pedicle screws306and307would have the locking caps330and335(shown inFIG.8, not shown here) still engaged to pedicle screw heads311and312, thus continuing to attach pedicle screws306and307to the existing spinal rod320.

FIG.12is an angled view of a spinal rod extension100mated to an existing spinal rod320of an existing two-level pedicle screw instrumentation construct, as also seen inFIG.8, in this figure prepared to be secured by a clamp400, in accordance with an illustrative embodiment. The clamp400can be any type of circular clamp known to those of skill in the art. In one embodiment, the clamp400can be a C-shaped partial ring with one side open such that the clamp could be slipped around both the connector portion105and the existing rod320from the side and then secured with one or more bolt(s) or screw(s)410. In another embodiment, the clamp400can be a ring-shape that has a hinge on one side and a latch on the other side so that the clamp400is able to slide around the connector portion105and the existing rod320and then be latched into a closed position, thus securing the connector portion105to the existing rod320. Another embodiment of the clamp400would be to use a strong woven fiber tape which could pass around both the connecter portion105and the existing rod320, and then be tied together or otherwise secured. Yet another embodiment of the clamp400can be a circular hose clamp that can be loosened and tightened via a screwdriver or other tool.

Clamp400is prepared to secure the spinal rod section105and its other sections comprising spinal rod extension100in its entirety to the existing spinal rod320. Once the clamp is positioned around the spinal rod extension and existing spinal rod, it will be tightened via bolts or set screws410which screw into threaded holes415and press against rod extension section105, thus securing spinal rod extension100to the existing spinal rod320. The bolts or set screws410can be tightened such that ends of the bolts or set screws contact the top surface of the spinal rod extension section105, thereby causing a friction fit between the connector portion105and the existing spinal rod320. The friction fit is maintained by the opening110and/or lip111(111not shown) and the relationship of the concave undersurface of rod extension connector portion105to the convex surface of existing rod320and the clamp400. In an alternative embodiment, the set screws410can be placed through threaded holes created in the rod extension section105itself, and create a frictional fit with existing rod320.

One or more clamps may be used. In an alternative embodiment, more than one clamp may be used. In another alternative embodiment, the clamp may be smaller or larger and may use one bolt or may use three or more bolts to secure the clamp(s) to the rods. In another alternative embodiment, clamp400may be of any style or configuration that results in spinal rod extension100being secured to existing spinal rod320.

FIG.13is an angled close-up view of a portion of spinal rod extension100mated to an existing spinal rod320of an existing two-level pedicle screw instrumentation construct, as also seen inFIG.8andFIG.12, in accordance with an illustrative embodiment. Clamp400is prepared to secure the spinal extension rod section105and its other sections comprising spinal rod extension100in its entirety to the existing spinal rod320. Once the clamp is positioned around the spinal rod extension and existing spinal rod, it will be tightened via bolts410which screw into threaded holes415and press against rod extension section105, thus securing spinal rod extension100to the existing spinal rod320. The curved concave undersurface of spinal rod extension section105is shown350to mate to the concave surface of existing spinal rod320.

FIG.14is a side view of a spinal rod extension100mated to an existing spinal rod320of an existing two-level pedicle screw instrumentation construct300, in accordance with an illustrative embodiment. Clamp400is securing the spinal rod section105and its other sections comprising spinal rod extension100in its entirety to the existing spinal rod320. The clamp is positioned around the spinal rod extension and existing spinal rod, and is tightened via bolts410which have been screwed into threaded holes415(shown inFIG.12, not shown here) and press against rod extension section105, thus securing spinal rod extension100to the existing spinal rod320.

FIG.15is an angled close-up view of a spinal rod extension100mated to an existing spinal rod320of an existing two-level pedicle screw instrumentation construct300, in accordance with an illustrative embodiment. Clamp400is securing the spinal rod section105and its other sections comprising spinal rod extension100in its entirety to the existing spinal rod320. The clamp is positioned around the spinal rod extension and existing spinal rod, and is tightened via bolts410which have been screwed into threaded holes415(shown inFIG.12, not shown here) and press against rod extension section105, thus securing spinal rod extension100to the existing spinal rod320.

FIG.16is a side view of a spinal rod extension100attached to new pedicle screws505and506and secured via clamp400to an existing spinal rod320of an existing two-level pedicle screw instrumentation construct300, in accordance with an illustrative embodiment. Clamp400is securing the spinal rod section105and its other sections comprising spinal rod extension100in its entirety to the existing spinal rod320. The clamp is positioned around the spinal rod extension and existing spinal rod, and is tightened via bolts410which have been screwed into threaded holes415(shown inFIG.12, not shown here) and press against rod extension section105, thus securing spinal rod extension100to the existing spinal rod320. Existing pedicle screws306and307are secured via locking caps to existing spinal rod320, the locking cap has been removed from pedicle screw305so that section105can pass through the pedicle screw head310, and new pedicle screws505and506are secured via locking caps to spinal rod extension section115, thus allowing for extension of an existing spinal instrumentation construct to a new level or levels. In this embodiment, existing spinal instrumentation is a two-level construct and the rod extension attaches to two new levels. In practice, the existing spinal instrumentation may be two or more levels and the extension can be attached to one or more new levels as clinically indicated. The spinal rod extension can be made in different lengths to accommodate different length constructs.

FIG.17is an angled view of a spinal rod extension100attached to new pedicle screws505and506and secured via clamp400to an existing spinal rod320of an existing two-level pedicle screw instrumentation construct300, in accordance with an illustrative embodiment. Clamp400is securing the spinal rod section105and its other sections comprising spinal rod extension100in its entirety to the existing spinal rod320. The clamp is positioned around the spinal rod extension and existing spinal rod, and is tightened via bolts410which have been screwed into threaded holes415(shown inFIG.12, not shown here) and press against rod extension section105, thus securing spinal rod extension100to the existing spinal rod320. Existing pedicle screws306and307are secured via locking caps325and330to existing spinal rod320, and new pedicle screws505and506are secured via locking caps525and530to spinal rod extension section115, thus allowing for extension of an existing spinal instrumentation construct to a new level or levels. The spinal rod extension passes through pedicle screw head310of pedicle screw305, with the locking cap that originally was present in screw head310having been permanently removed. In an alternative embodiment, locking cap325could be removed from pedicle screw head311of pedicle screw306and a longer section105of spinal rod extension100could pass through both screw heads310and311and the spinal rod extension secured to the existing spinal rod in one or more places with one or more clamps. In the embodiment shown inFIG.17, the existing spinal instrumentation is a two-level construct spanning two intervertebral disk spaces and the spinal rod extension attaches to two new levels. In practice, the existing spinal instrumentation may be two or more levels and the spinal rod extension can be attached to one or more new levels as clinically indicated. The spinal rod extension can be made in different lengths to accommodate different length constructs.

FIG.18is a top view of a spinal rod extension100attached to new pedicle screws505and506and secured via clamp400to an existing spinal rod320of an existing two-level pedicle screw instrumentation construct300, in accordance with an illustrative embodiment. Clamp400is securing the spinal rod section105and its other sections comprising spinal rod extension100in its entirety to the existing spinal rod320. The clamp is positioned around the spinal rod extension and existing spinal rod, and is tightened via bolts410which have been screwed into threaded holes415(shown inFIG.12, not shown here) and press against rod extension section105, thus securing spinal rod extension100to the existing spinal rod320. Existing pedicle screws306and307are secured via locking caps325and330to existing spinal rod320, and new pedicle screws505and506are secured via locking caps525and530to spinal rod extension section115, thus allowing for extension of an existing spinal instrumentation construct to a new level or levels. The spinal rod extension passes through pedicle screw head310of pedicle screw305, with the locking cap that originally was present in screw head310having been permanently removed. In an alternative embodiment, locking cap325could be removed from pedicle screw head311of pedicle screw306and a longer section105of spinal rod extension100could pass through both screw heads310and311and the spinal rod extension secured to the existing spinal rod in one or more places with one or more clamps. In an alternative embodiment, section105of spinal rod extension100can pass through more than two existing pedicle screw heads. In the embodiment shown inFIG.18, the existing spinal instrumentation is a two-level construct spanning two intervertebral disk spaces and the spinal rod extension attaches to two new vertebral levels via pedicle screws. In practice, the existing spinal instrumentation may be two or more levels and the spinal rod extension can be attached to one or more new levels as clinically indicated. The spinal rod extension can be made in different lengths to accommodate different length constructs.

As discussed above with reference toFIG.18, the spinal rod extension passes through pedicle screw head310of pedicle screw305, with the locking cap that originally was present in screw head310having been permanently removed. In an alternative embodiment, the locking cap that was originally present in screw head310may be temporarily removed to accommodate the spinal rod extension. Upon placement of the spinal rod extension, the locking cap can be reinserted into the screw head310and used to secure or help secure the existing spinal rod.

FIG.19is a flow diagram depicting a process for mounting a spinal rod extension to an existing spinal rod in accordance with an illustrative embodiment. In alternative embodiments, fewer, additional, and/or different operations may be performed. Additionally, the use of a flow diagram is not meant to be limiting with respect to the order of operations performed. In an operation600, the surgeon accesses an existing spinal rod implant in a patient. Specifically, the surgeon can surgically approach the top or the bottom of the existing spinal rod and terminal pedicle screw, depending on where the spinal rod extension is to be placed.

In an operation605, the surgeon removes one or more set screws (or locking caps) from one or more pedicle screws that secure the existing spinal rod. Upon removal of the one or more set screws, the existing spinal rod is exposed. In an operation610, the surgeon inserts the spinal rod extension through the one or more existing pedicle screws from which the one or more set screws were removed. Specifically, the spinal rod extension is placed dorsally onto the existing spinal rod, passing through the pedicle screw u-shaped head(s) from with the set screw(s) have been removed. In an illustrative embodiment, the spinal rod extension is positioned so that a lip or opening of the spinal rod extension engages an end of the existing spinal rod that extends past a terminal pedicle screw that was used to secure the existing spinal rod.

In an operation615, the spinal rod extension is secured to the existing spinal rod implant. In an illustrative embodiment, the spinal rod extension is secured to the existing spinal rod with one or more clamps. In alternative embodiments, a different securing method may be used. In an operation620, the surgeon inserts fasteners to further secure the spinal rod extension to the existing spinal rod.

In an operation625, the surgeon secures the rod portion of the spinal rod extension to the patient. In an illustrative embodiment, the spinal rod extension is attached to new pedicle screws that are placed cephalad or caudal to the existing spinal rod, depending on the needs of the patient. The rod portion of the spinal rod extension can be tunneled beneath the skin, subcutaneous tissues, and muscle of the patient in order to attach to the new pedicle screws that have been placed percutaneously. Alternatively, the rod portion of the spinal rod implant can be attached to new pedicle screws that have been placed through a conventional open posterior approach.

FIG.20Ais an angled top view of an existing two-level pedicle screw instrumentation construct600, in accordance with an illustrative embodiment. The pedicle screw instrumentation construct600depicted here would span two intervertebral disk levels while performing a two-level instrumented spinal fusion and includes an existing spinal rod320attached to three pedicle screws605,606, and607. The pedicle screws include a threaded shaft615that is screwed into a vertebra of a patient (not shown) and a u-shaped pedicle screw head610,611, and612that is configured to receive a spinal rod320. Depending on the implementation, the u-shaped pedicle screw heads610,611, and612may be pivotally mounted to the threaded shaft615of the pedicle screw. At least an upper portion of the u-shaped pedicle screw heads610,611, and612is threaded and configured to receive a locking cap625,630, and635. The locking cap may be alternatively referred to as a set screw. The existing spinal rod320is secured to the pedicle screws by locking caps (or set screws)625,630, and635. The set screws625,630, and635are used to secure the existing spinal rod320within the u-shaped pedicle screw heads610,611, and612of the pedicle screws605,606, and607. Pedicle screw heads610,611, and612contain a surface feature610a,611a,612aof variable shape. In the depicted embodiment, the surface features610a,611a, and612aare in the form of a semi-spherical void or indentation designed to allow instruments to be reversibly and temporarily attached to the pedicle screw head. Alternatively, the surface feature can be square, rectangular, triangular, etc. in shape, and may be in the form of an indentation or a protrusion. The surface features610a,611a, and612acreate a connection point for instruments which are typically used for pedicle screw insertion and/or reduction of the rod into the pedicle screw head during a surgery, after which the instrument(s) is/are detached from the pedicle screw head.

FIG.20Bis an angled top view of the existing two-level pedicle screw instrumentation construct600depicted inFIG.20A, with set screw635now removed from screw head612, in accordance with an illustrative embodiment.

FIG.20Cis an angled top view of the existing two-level pedicle screw instrumentation construct600depicted inFIGS.20A and20B, with set screw635removed from screw head612in anticipation of a rod extension100being placed onto existing spinal rod320through pedicle screw head612, in accordance with an illustrative embodiment. Locking cap635has been removed from pedicle screw head612of pedicle screw607in order to create space for the spinal rod extension100to mate to existing spinal rod320. Pedicle screws605and606have locking caps625and630still engaged to pedicle screw heads610and611, thus continuing to attach to rod320. In an illustrative embodiment, a bottom portion of section105(i.e., connector portion) of the rod extension100can be curved or concave such that connector portion105form-fits the convex contour of the existing spinal rod320(seeFIG.6and associated description). As such, when mounted to the existing spinal rod320(seeFIG.20D), the connector portion105can be flush or nearly flush with or within a top edge of the u-shaped pedicle screw head612. The rod portion115of the rod extension100is then available to be secured to newly placed pedicle screws during a revision surgery (as shown inFIGS.16-18).

FIG.20Dis an angled top view of the existing two-level pedicle screw instrumentation construct600depicted inFIGS.20A and20B, with set screw635removed from the pedicle screw head612, now with the connector portion105of rod extension100placed on the existing spinal rod320and passing through pedicle screw head612, in accordance with an illustrative embodiment. The rod portion115of the rod extension100is then available to be secured to newly placed pedicle screws during a revision surgery (as shown inFIGS.16-18).

FIGS.21A-21Edepict various views of a pedicle screw head connector700in accordance with illustrative embodiments. Pedicle screw head connector700attaches to an existing pedicle screw head and secures a rod extension to an existing rod (seeFIGS.24A-24BandFIGS.25A-25C).FIG.21Adepicts an end wall705of the pedicle screw head connector700, in accordance with an illustrative embodiment. An upper portion706of the end wall705includes a threaded portion707that accommodates a set screw (seeFIG.22A). A lower portion708of the end wall705includes a connector surface feature709that is designed to mate with a surface feature of a pedicle screw head, such as the surface feature612A depicted inFIG.20A, and later depicted inFIG.22A. In an illustrative embodiment, the connector surface feature709is in the form of a semi-spherical protuberance that is sized to mate with a semi-spherical indentation on the pedicle screw head. Alternatively, the connector surface feature709may be an indentation that mates with a protuberance on the pedicle screw head. Additionally, regardless of whether the connector surface feature709is a protuberance or indentation, the connector surface feature may have a different shape such as square, rectangular, triangular, etc.

FIG.21Aalso depicts a post720that extends from a body of the end wall705and that is used to secure the end wall705to a cross connector as described below. In an illustrative embodiment, each end wall includes a pair of posts (i.e., one on each side) such that the end wall can be mounted to a front cross connector and a rear cross connector. The post720can be integrally formed with the end wall705. Alternatively, the post720may be mounted into a hole in the body of the end wall705. While the post720is depicted as cylindrical, it is to be understood that other shapes (e.g., square, rectangular, star-shaped, etc.) may be used in other embodiments.

FIG.21Bdepicts an angled top view of a pedicle screw head connector700that includes a pair of end walls705joined by a pair of cross connectors715that connect to end walls705by a pair of posts720, the ends of which are visible, in accordance with an illustrative embodiment. The posts720are depicted in greater detail inFIGS.22A-22EandFIGS.23A-23D. As described herein, the posts720allow the end walls705to pivot (or articulate) relative to the cross connectors715.FIG.21Cis an angled plane view of pedicle screw head connector700with the pair of end walls705and the cross connectors715that connect to the end walls705by posts720, the ends of which are visible, in accordance with an illustrative embodiment. A single connector surface feature709that is designed to mate with a surface feature of a pedicle screw head, such as612A as depicted inFIG.20A, is visible on one of the end walls705, but is not visible on the other end wall705due to the angle of the drawing.FIG.21Dis a bottom view of the pedicle screw head connector700with end walls705and cross connectors715that connect to the end walls705by posts720, the ends of which are visible, in accordance with an illustrative embodiment. Connector surface features709that are designed to mate with surface features of a pedicle screw head, such as612A depicted inFIG.20A, are also visible.FIG.21Eis a top view of the pedicle screw head connector700with the end walls705and cross connectors715that connect to the end walls705by the posts720, the ends of which are visible, in accordance with an illustrative embodiment.

FIG.22Ais an angled top view of the pedicle screw head connector700along with a set screw636and pedicle screw607, in accordance with an illustrative embodiment. End walls705of the screw connector700are depicted in an angled configuration, articulating (or pivoting) through posts720, the ends of which are shown here. In an illustrative embodiment, the posts720are integrally connected to the end walls705. In an alternative embodiment, each post720is a cylindrical rod that extends through a hole in the first cross connector715, through a cylindrical channel in the upper portion706of an end wall705, and through a hole in the second cross connector715. Alternatively, the pedicle screw head connector700may utilize 4 posts that extend through holes in the cross connectors715and into partial cylindrical channels in the upper portions706of the end walls705. The posts720can be connected to the cross connectors715via a friction fit, via pins (e.g. cotter pins placed through holes in the protruding ends of the posts720) that prevent the cross connectors715from coming off of the posts720, and/or by any other method.

The ability to pivot the end walls705allows the pedicle screw head connector700to slide onto pedicle screw head612of pedicle screw607, as shown inFIG.22B. When the angling of the end walls705is reversed (i.e., when lower portions of the end walls705are pivoted toward the pedicle screw head, as seen inFIGS.22D-22E), a surface feature709(fromFIGS.21A and21C) on the end walls705mates with a reciprocal surface feature on the pedicle screw head, creating a tight interference fit that is held by set screw636. The set screw636is inserted into the threaded portion707(seeFIGS.21A and21B) of the screw head connector700, which forces the upper threaded portion of end walls705away from each other, reversing the articulation depicted inFIGS.22A-22C. As shown, the surface features709of the end walls and the surface features612aof the pedicle screw head are sized such that the screw head connector cannot be mounted to the screw head while end walls are orthogonal to the pair of cross connectors. The angling (or pivoting) of the end walls relative to the cross connectors allows the pedicle screw connector to slide a top surface of the pedicle screw head.

FIG.22Cdepicts the pedicle screw head connector700slid onto the pedicle screw head612of pedicle screw607, in anticipation of set screw636being inserted into threaded portions707of the end walls705.FIG.22Ddepicts the pedicle screw head connector700slid onto the pedicle screw head612of pedicle screw607, now with set screw636being inserted into screw head connector700via screw threads707(seeFIGS.21A and21B), in accordance with an illustrative embodiment. The process of set screw636engaging threaded portions707of the end walls705of the pedicle screw head connector700reverses the angulation of end walls705, which in turn causes the inner surfaces of the end walls705(that include the surface features709, seeFIGS.21A and21C) to tightly engage and thus connect to the outer surfaces of the pedicle screw head612(that contain reciprocal surface features). Thus, insertion of set screw636creates an interference fit between the interfacing surfaces of the end walls705and the pedicle screw heads612, and this fit is further enhanced by the reciprocal fit of the surface features709(fromFIGS.21A and21C) of the end walls and the surface features of the pedicle screw head. The cumulative effect of these interfaces is to establish a connection of screw head connector700to pedicle screw head612.FIG.22Edepicts set screw636fully inserted into screw head connector700, which fully establishes the connection between screw head connector700and pedicle screw head612, in accordance with an illustrative embodiment. Not shown is the presence of rod320and mated rod extension100in slot769of pedicle screw head612; these features are shown inFIG.24B.

FIG.23Adepicts a cephalad-caudal or end view of pedicle screw head connector700with end walls705, the set screw636not yet advanced into screw head connector700, and the pedicle screw607with pedicle screw head612, in accordance with an illustrative embodiment. The end walls705are in an angled position, allowing placement of screw head connector700onto screw head612in anticipation of placement of set screw636, as depicted inFIG.23B, in accordance with an illustrative embodiment. In one embodiment, the angled configuration can refer to an angle of greater than 90 degrees (e.g., an angle between 90 degrees and 180 degrees) between each of the end walls and the cross connectors (as shown in the view ofFIG.23A). Reversing the angled configuration can result in an angle of approximately 90 degrees (e.g., an angle between 85-95 degrees) between each of the end walls and the cross connectors (as shown inFIG.23C). In alternative embodiments, different angles may be used.

FIG.23Cdepicts a cephalad-caudal view of pedicle screw head connector700with angulation of the end walls705reversed as set screw636is inserted, and a pedicle screw607with pedicle screw head612, in accordance with an illustrative embodiment. Pedicle screw head connector700is attaching to pedicle screw head612of pedicle screw607, due to set screw636being inserted into screw head connector700via screw threads707(seeFIGS.21A and21B). The process of set screw636engaging threaded portions707of the end walls705of screw head connector707(seeFIGS.21A and21B, andFIG.22D) reverses the angulation of the end walls705, which in turn causes the inner surfaces of the end walls705(that include surface features709, seeFIGS.21A and21C) to tightly engage and thus connect to the outer surfaces of screw head612(that contain reciprocal surface features, seeFIGS.20A and22A). The insertion of set screw636reverses the angulation of the end walls705, creating an interference fit between the interfacing surfaces of end walls705and pedicle screw head612, and this fit is further enhanced by the reciprocal fit of the surface features as described herein. The cumulative effect of these interfaces establishes a connection of screw head connector700with pedicle screw head612.FIG.22Edepicts set screw636fully inserted into screw head connector700, which fully establishes the connection between screw head connector700and pedicle screw head612. Not shown is the presence of rod320and mated rod extension100in slot769(shown earlier inFIGS.20C and20D, and later inFIG.24B).

FIG.24Ais an angled side view of screw head connector700, pedicle screw607with pedicle screw head612, existing rod320, and rod extension100, in accordance with an illustrative embodiment. Rod extension100is passed through pedicle screw head612, in anticipation of screw head connector700being attached to screw head612.

FIG.24Bis an angled side view of screw head connector700, pedicle screw607with pedicle screw head612, existing rod320, and rod extension100, in accordance with an illustrative embodiment. Rod extension100is passed through pedicle screw head612, now with screw head connector700secured to screw head612by virtue of set screw636placement (seeFIGS.23A—23D), which in turn presses rod extension100firmly against existing rod320and secures rod extension100and existing rod320within pedicle screw head612.

When set screw636is inserted into the threaded portion of screw head connector700(seeFIGS.21A-21B), a surface of set screw636presses against an upper surface of rod extension100, which in turn presses a surface of rod extension100to a surface of existing rod320and this in turn presses a surface of existing rod320to a surface of pedicle screw head612, creating a tight frictional fit amongst screw head connector700, set screw636, screw head612, existing rod320, and rod extension100. When set screw636is fully inserted, this creates a frictional fit between surface feature709(seeFIG.21AandFIG.21C) of the screw head connector and the corresponding surface feature612a(seeFIG.20AandFIG.22A) of the pedicle screw head612. This further secures screw head connector700, pedicle screw head612and associated pedicle screw607, existing rod320, and rod extension100to each other via frictional forces (seeFIGS.22C and22Dand associated descriptions). The rod portion115of rod extension100is then available to be secured to newly placed pedicle screws during a revision surgery (as shown inFIGS.16-18).

FIG.25Ais an angled top view of screw head connector700, pedicle screw607with pedicle screw head612, existing rod320(seeFIG.20D), and rod extension100(seeFIG.20D), in accordance with an illustrative embodiment. The connector portion105of rod extension100is passed through pedicle screw head612(seeFIGS.1,2,7,8, and11) in anticipation of screw head connector700being attached to screw head612.

FIG.25Bis an angled top view of screw head connector700, set screw636, pedicle screw607with pedicle screw head612, existing rod320, and rod extension100, in accordance with an illustrative embodiment. InFIG.25B, the screw head connector700has been placed onto screw head612, in anticipation of being secured to screw head612by set screw636.

FIG.25Cdepicts an angled top view of screw head connector700, set screw636, pedicle screw607with pedicle screw head612, existing rod320, and rod extension100, in accordance with an illustrative embodiment. Screw head connector700is secured to screw head612by virtue of set screw636placement (seeFIGS.22A-22DandFIGS.23A-23D), which in turn presses a surface of rod extension100firmly against a surface of existing rod320which is in turn pressed against a surface of screw head612, securing rod extension100and existing rod320within pedicle screw head612.

FIG.26Adepicts a cephalad-caudal or end view of an alternative embodiment of a screw head connector800and a pedicle screw head850in a disassembled configuration, in accordance with illustrative embodiments. Pedicle screw head850includes a surface feature850aof variable shape, here a notch, designed to allow instruments to be reversibly and temporarily attached to the pedicle screw head. The surface feature850ais positioned on the end walls that extend from a cap of the screw head connector800. In alternative implementations, the surface feature on the pedicle screw head850may be a protuberance as opposed to an indentation, and the protuberance/indentation can have another shape and/or dimension. The surface feature850acreates a connection point for instruments which are typically used for pedicle screw insertion and/or reduction of the rod into the pedicle screw head during a surgery, after which the instrument(s) is/are detached from the pedicle screw head. Screw head connector800includes protuberances805that are designed to mate with the surface features850aof the pedicle screw head850.

FIG.26Bdepicts an angled bottom view of screw head connector800and a pedicle screw head850in a disassembled configuration, in accordance with an illustrative embodiment. As discussed above, the pedicle screw head850includes the surface feature850a, designed to allow instruments to be reversibly and temporarily attached to the pedicle screw head. The surface feature850acreates a connection point for instruments which are typically used for pedicle screw insertion and/or reduction of the rod into the pedicle screw head during a surgery, after which the instrument(s) is/are detached from the pedicle screw head. Screw head connector800includes surface features805that are designed to mate with the surface features850aof the pedicle screw head. The cap of the screw head connector800also includes a hole810with threads807designed to accommodate a set screw.

FIG.26Cis an angled bottom view of screw head connector800and a pedicle screw head850in an assembling configuration, in accordance with an illustrative embodiment. The surface features805of the screw head connector800are now shown in the process of mating with the surface features850aof the pedicle screw head850. As shown, in this embodiment, the end walls of the pedicle screw head connector800are rigid and do not pivot relative to the cap of the pedicle screw head connector800. The assembly is therefore performed by sliding the pedicle screw head connector800onto the pedicle screw head850such that the surface features850amate with the surface features805.

FIG.26Dis an angled bottom view of screw head connector800and a pedicle screw head850in an assembled configuration, in accordance with an illustrative embodiment. Surface features805of the pedicle screw head connector850are now shown mating with the surface features850ain pedicle screw head850as seen inFIGS.26A and26B.

FIG.27Adepicts an end view of screw head connector800and a pedicle screw head850in an assembled configuration in anticipation of set screw636placement, in accordance with an illustrative embodiment. An existing rod (not shown, seeFIG.27C) and a rod extension (not shown, seeFIG.27C) will pass through a slot851in pedicle screw head850(seeFIG.27CandFIGS.28A-28C).

FIG.27Bdepicts an end view of screw head connector800and a pedicle screw head850in an assembled configuration, with set screw636now placed into the screw head connector threads (SeeFIG.26B) of screw head connector800and threads of the pedicle screw head850, in accordance with an illustrative embodiment. An existing rod (not shown, seeFIG.27C) and a rod extension (not shown, seeFIG.27C) will pass through slot851in pedicle screw head850(seeFIG.27CandFIGS.28A-28C).

FIG.27Cdepicts an end view of screw head connector800and a pedicle screw head850in an assembled configuration, now with rod extension100and existing rod320depicted in opening851(fromFIGS.27A and27B) in pedicle screw head850, in accordance with an illustrative embodiment. A surface of set screw636presses against a surface of rod extension100(see alsoFIG.28C), which in turn presses against a surface of existing rod320, which in turn presses against a surface of pedicle screw head850, thus creating a tight frictional fit amongst screw head connector800, screw head850, rod extension100, and existing rod320(seeFIGS.28A-28C).

FIG.28Adepicts an angled top view of screw head connector800, pedicle screw815with pedicle screw head850, existing rod320(seeFIG.20D), and rod extension100(seeFIG.20Din accordance with an illustrative embodiment. Existing rod320is still attached to pedicle screw head850via set screw635. Screw head connector800and associated set screw636and rod extension100are in a disassembled position, in anticipation of set screw635being removed, allowing placement of rod extension100through pedicle screw head850and onto existing rod320(analogous to the configuration seen inFIG.20D).

FIG.28Bdepicts an angled top view of screw head connector800, pedicle screw815with pedicle screw head850, existing rod320, and rod extension100, in accordance with an illustrative embodiment. Set screw635has been removed from pedicle screw head850, which will allow for the connector portion105of rod extension100to be placed through pedicle screw head850and rest on existing rod320(analogous to the configuration seen inFIG.20D). Screw head connector800and associated set screw636and rod extension100are in a disassembled position, in anticipation of placement of the connector portion105of rod extension100through pedicle screw head850and onto existing rod320(analogous to the configuration seen inFIG.20D).

FIG.28Cdepicts an angled top view of screw head connector800, pedicle screw815with pedicle screw head850, existing rod320, and rod extension100, in accordance with an illustrative embodiment. The connector portion105of rod extension100has been placed through pedicle screw head850and rests on existing rod320(analogous to the configuration seen inFIG.20D). Screw head connector800is secured to pedicle screw head850by set screw636, which when inserted presses against an upper surface of rod extension section105, which in turn presses a surface of rod extension105to a surface of existing rod320and presses a surface of existing rod320to a surface of pedicle screw head850, creating a tight frictional fit amongst screw head connector850, set screw636, screw head850, existing rod320, and rod extension100. When set screw636is tightly secured against a surface of rod extension100, this creates a further frictional fit between a surface of surface feature805(seeFIGS.26A-26D) and an opposing surface feature850a(seeFIGS.26A-26D), which are forced in opposite directions, further securing screw head connector800, screw head850and associated pedicle screw815, existing rod320, and rod extension100to each other via frictional forces. The rod portion115of rod extension100is then available to be secured to newly placed pedicle screws during a revision surgery (seeFIGS.16-18).

FIG.29is a flow diagram depicting a process for mounting a spinal rod extension to an existing spinal rod in accordance with an illustrative embodiment. In alternative embodiments, fewer, additional, and/or different operations may be performed. Additionally, the use of a flow diagram is not meant to be limiting with respect to the order of operations performed.

In an operation900, the surgeon accesses an existing spinal rod implant in a patient. Specifically, the surgeon can surgically approach the top or the bottom of the existing spinal rod and terminal pedicle screw, depending on where the spinal rod extension is to be placed. In an operation905, the surgeon removes one or more set screws (or locking caps) from one or more pedicle screws that secure the existing spinal rod. Upon removal of the one or more set screws, all or a portion of the existing spinal rod is exposed.

In an operation910, the surgeon inserts a connector portion of a spinal rod extension through the one or more existing pedicle screws from which the one or more set screws were removed. Specifically, the connector portion of the spinal rod extension is placed dorsally onto the existing spinal rod, passing through the pedicle screw u-shaped head(s) from which the set screw(s) have been removed.

In an operation915, the connector portion of the spinal rod extension is secured to the existing spinal rod implant. In an illustrative embodiment, the spinal rod extension is secured to the existing spinal rod with one or more screw head connectors, as described herein. In alternative embodiments, a different securing method may be used.

In an operation920, the surgeon secures the rod portion of the spinal rod extension to the patient. In an illustrative embodiment, the rod portion of the spinal rod extension is attached to new pedicle screws that are placed cephalad or caudal to the existing spinal rod, depending on the needs of the patient. The rod portion of the spinal rod extension can be tunneled beneath the skin, subcutaneous tissues, and muscle of the patient in order to attach to the new pedicle screws that have been placed percutaneously. Alternatively, the rod portion of the spinal rod implant can be attached to new pedicle screws that have been placed through a conventional open posterior approach.

The spinal rod extensions described herein can be made of the same materials as existing spinal instrumentation systems, which include but are not limited to titanium, titanium alloy, cobalt chrome, stainless steel, and polyether ether ketone (PEEK). The spinal rod extension can be provided as a straight version (i.e., a version in which the rod portion of the spinal rod extension is substantially straight) that can be placed as-is into the patient. The spinal rod extension can also be flexible such that the rod portion of the spinal rod extension can be bent prior to implantation in order to match the patient's anatomy. The spinal rod extension can also be provided as a precontoured version in which the rod portion is pre-bent to match a patient's lordotic or kyphotic spine segment. The spinal rod extension can also include an articulation such that the portion of the spinal rod extension that is attached to new pedicle screws can be angled with respect to the portion of the rod extension that is attached to the previously placed rod.

The foregoing description of illustrative embodiments has been presented for purposes of illustration and of description. It is not intended to be exhaustive or limiting with respect to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the disclosed embodiments. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.